## 3.6 Absolute Value Functions

Learning objectives.

In this section, you will:

- Graph an absolute value function.
- Solve an absolute value equation.

Until the 1920s, the so-called spiral nebulae were believed to be clouds of dust and gas in our own galaxy, some tens of thousands of light years away. Then, astronomer Edwin Hubble proved that these objects are galaxies in their own right, at distances of millions of light years. Today, astronomers can detect galaxies that are billions of light years away. Distances in the universe can be measured in all directions. As such, it is useful to consider distance as an absolute value function. In this section, we will continue our investigation of absolute value functions .

## Understanding Absolute Value

Recall that in its basic form f ( x ) = | x | , f ( x ) = | x | , the absolute value function is one of our toolkit functions. The absolute value function is commonly thought of as providing the distance the number is from zero on a number line. Algebraically, for whatever the input value is, the output is the value without regard to sign. Knowing this, we can use absolute value functions to solve some kinds of real-world problems.

## Absolute Value Function

The absolute value function can be defined as a piecewise function

## Using Absolute Value to Determine Resistance

Electrical parts, such as resistors and capacitors, come with specified values of their operating parameters: resistance, capacitance, etc. However, due to imprecision in manufacturing, the actual values of these parameters vary somewhat from piece to piece, even when they are supposed to be the same. The best that manufacturers can do is to try to guarantee that the variations will stay within a specified range, often ±1%, ± 5%, ±1%, ± 5%, or ± 10% . ± 10% .

Suppose we have a resistor rated at 680 ohms, ± 5 % . ± 5 % . Use the absolute value function to express the range of possible values of the actual resistance.

We can find that 5% of 680 ohms is 34 ohms. The absolute value of the difference between the actual and nominal resistance should not exceed the stated variability, so, with the resistance R R in ohms,

Students who score within 20 points of 80 will pass a test. Write this as a distance from 80 using absolute value notation.

## Graphing an Absolute Value Function

The most significant feature of the absolute value graph is the corner point at which the graph changes direction. This point is shown at the origin in Figure 2 .

Figure 3 shows the graph of y = 2 | x – 3 | + 4. y = 2 | x – 3 | + 4. The graph of y = | x | y = | x | has been shifted right 3 units, vertically stretched by a factor of 2, and shifted up 4 units. This means that the corner point is located at ( 3 , 4 ) ( 3 , 4 ) for this transformed function.

## Writing an Equation for an Absolute Value Function Given a Graph

Write an equation for the function graphed in Figure 4 .

The basic absolute value function changes direction at the origin, so this graph has been shifted to the right 3 units and down 2 units from the basic toolkit function. See Figure 5 .

We also notice that the graph appears vertically stretched, because the width of the final graph on a horizontal line is not equal to 2 times the vertical distance from the corner to this line, as it would be for an unstretched absolute value function. Instead, the width is equal to 1 times the vertical distance as shown in Figure 6 .

From this information we can write the equation

Note that these equations are algebraically equivalent—the stretch for an absolute value function can be written interchangeably as a vertical or horizontal stretch or compression. Note also that if the vertical stretch factor is negative, there is also a reflection about the x-axis.

If we couldn’t observe the stretch of the function from the graphs, could we algebraically determine it?

Yes. If we are unable to determine the stretch based on the width of the graph, we can solve for the stretch factor by putting in a known pair of values for x x and f ( x ) . f ( x ) .

Now substituting in the point (1, 2)

Write the equation for the absolute value function that is horizontally shifted left 2 units, is vertically reflected, and vertically shifted up 3 units.

Do the graphs of absolute value functions always intersect the vertical axis? The horizontal axis?

Yes, they always intersect the vertical axis. The graph of an absolute value function will intersect the vertical axis when the input is zero.

No, they do not always intersect the horizontal axis. The graph may or may not intersect the horizontal axis, depending on how the graph has been shifted and reflected. It is possible for the absolute value function to intersect the horizontal axis at zero, one, or two points (see Figure 7 ).

## Solving an Absolute Value Equation

In Other Type of Equations , we touched on the concepts of absolute value equations. Now that we understand a little more about their graphs, we can take another look at these types of equations. Now that we can graph an absolute value function, we will learn how to solve an absolute value equation. To solve an equation such as 8 = | 2 x − 6 | , 8 = | 2 x − 6 | , we notice that the absolute value will be equal to 8 if the quantity inside the absolute value is 8 or -8. This leads to two different equations we can solve independently.

Knowing how to solve problems involving absolute value functions is useful. For example, we may need to identify numbers or points on a line that are at a specified distance from a given reference point.

An absolute value equation is an equation in which the unknown variable appears in absolute value bars. For example,

## Solutions to Absolute Value Equations

For real numbers A A and B B , an equation of the form | A | = B , | A | = B , with B ≥ 0 , B ≥ 0 , will have solutions when A = B A = B or A = − B . A = − B . If B < 0 , B < 0 , the equation | A | = B | A | = B has no solution.

Given the formula for an absolute value function, find the horizontal intercepts of its graph .

- Isolate the absolute value term.
- Use | A | = B | A | = B to write A = B A = B or −A = B , −A = B , assuming B > 0. B > 0.
- Solve for x . x .

## Finding the Zeros of an Absolute Value Function

For the function f ( x ) = | 4 x + 1 | − 7 , f ( x ) = | 4 x + 1 | − 7 , find the values of x x such that f ( x ) = 0. f ( x ) = 0.

The function outputs 0 when x = 3 2 x = 3 2 or x = − 2. x = − 2. See Figure 8 .

For the function f ( x ) = | 2 x − 1 | − 3 , f ( x ) = | 2 x − 1 | − 3 , find the values of x x such that f ( x ) = 0. f ( x ) = 0.

Should we always expect two answers when solving | A | = B ? | A | = B ?

No. We may find one, two, or even no answers. For example, there is no solution to 2 + | 3 x − 5 | = 1. 2 + | 3 x − 5 | = 1.

Access these online resources for additional instruction and practice with absolute value.

- Graphing Absolute Value Functions
- Graphing Absolute Value Functions 2

## 3.6 Section Exercises

How do you solve an absolute value equation?

How can you tell whether an absolute value function has two x -intercepts without graphing the function?

When solving an absolute value function, the isolated absolute value term is equal to a negative number. What does that tell you about the graph of the absolute value function?

How can you use the graph of an absolute value function to determine the x -values for which the function values are negative?

Describe all numbers x x that are at a distance of 4 from the number 8. Express this set of numbers using absolute value notation.

Describe all numbers x x that are at a distance of 1 2 1 2 from the number −4. Express this set of numbers using absolute value notation.

Describe the situation in which the distance that point x x is from 10 is at least 15 units. Express this set of numbers using absolute value notation.

Find all function values f ( x ) f ( x ) such that the distance from f ( x ) f ( x ) to the value 8 is less than 0.03 units. Express this set of numbers using absolute value notation.

For the following exercises, find the x - and y -intercepts of the graphs of each function.

f ( x ) = 4 | x − 3 | + 4 f ( x ) = 4 | x − 3 | + 4

f ( x ) = − 3 | x − 2 | − 1 f ( x ) = − 3 | x − 2 | − 1

f ( x ) = − 2 | x + 1 | + 6 f ( x ) = − 2 | x + 1 | + 6

f ( x ) = − 5 | x + 2 | + 15 f ( x ) = − 5 | x + 2 | + 15

f ( x ) = 2 | x − 1 | − 6 f ( x ) = 2 | x − 1 | − 6

f ( x ) = | − 2 x + 1 | − 13 f ( x ) = | − 2 x + 1 | − 13

f ( x ) = − | x − 9 | + 16 f ( x ) = − | x − 9 | + 16

For the following exercises, graph the absolute value function. Plot at least five points by hand for each graph.

y = | x − 1 | y = | x − 1 |

y = | x + 1 | y = | x + 1 |

y = | x | + 1 y = | x | + 1

For the following exercises, graph the given functions by hand.

y = | x | − 2 y = | x | − 2

y = − | x | y = − | x |

y = − | x | − 2 y = − | x | − 2

y = − | x − 3 | − 2 y = − | x − 3 | − 2

f ( x ) = − | x − 1 | − 2 f ( x ) = − | x − 1 | − 2

f ( x ) = − | x + 3 | + 4 f ( x ) = − | x + 3 | + 4

f ( x ) = 2 | x + 3 | + 1 f ( x ) = 2 | x + 3 | + 1

f ( x ) = 3 | x − 2 | + 3 f ( x ) = 3 | x − 2 | + 3

f ( x ) = | 2 x − 4 | − 3 f ( x ) = | 2 x − 4 | − 3

f ( x ) = | 3 x + 9 | + 2 f ( x ) = | 3 x + 9 | + 2

f ( x ) = − | x − 1 | − 3 f ( x ) = − | x − 1 | − 3

f ( x ) = − | x + 4 | − 3 f ( x ) = − | x + 4 | − 3

f ( x ) = 1 2 | x + 4 | − 3 f ( x ) = 1 2 | x + 4 | − 3

Use a graphing utility to graph f ( x ) = 10 | x − 2 | f ( x ) = 10 | x − 2 | on the viewing window [ 0 , 4 ] . [ 0 , 4 ] . Identify the corresponding range. Show the graph.

Use a graphing utility to graph f ( x ) = − 100 | x | + 100 f ( x ) = − 100 | x | + 100 on the viewing window [ − 5 , 5 ] . [ − 5 , 5 ] . Identify the corresponding range. Show the graph.

For the following exercises, graph each function using a graphing utility. Specify the viewing window.

f ( x ) = − 0.1 | 0.1 ( 0.2 − x ) | + 0.3 f ( x ) = − 0.1 | 0.1 ( 0.2 − x ) | + 0.3

f ( x ) = 4 × 10 9 | x − ( 5 × 10 9 ) | + 2 × 10 9 f ( x ) = 4 × 10 9 | x − ( 5 × 10 9 ) | + 2 × 10 9

For the following exercises, solve the inequality.

If possible, find all values of a a such that there are no x - x - intercepts for f ( x ) = 2 | x + 1 | + a . f ( x ) = 2 | x + 1 | + a .

If possible, find all values of a a such that there are no y y -intercepts for f ( x ) = 2 | x + 1 | + a . f ( x ) = 2 | x + 1 | + a .

## Real-World Applications

Cities A and B are on the same east-west line. Assume that city A is located at the origin. If the distance from city A to city B is at least 100 miles and x x represents the distance from city B to city A, express this using absolute value notation.

The true proportion p p of people who give a favorable rating to Congress is 8% with a margin of error of 1.5%. Describe this statement using an absolute value equation.

Students who score within 18 points of the number 82 will pass a particular test. Write this statement using absolute value notation and use the variable x x for the score.

A machinist must produce a bearing that is within 0.01 inches of the correct diameter of 5.0 inches. Using x x as the diameter of the bearing, write this statement using absolute value notation.

The tolerance for a ball bearing is 0.01. If the true diameter of the bearing is to be 2.0 inches and the measured value of the diameter is x x inches, express the tolerance using absolute value notation.

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Chapter 3 Functions

## 3.7 Absolute Value Functions

Learning objectives.

In this section, you will:

- Graph an absolute value function.
- Solve an absolute value equation.

Until the 1920s, the so-called spiral nebulae were believed to be clouds of dust and gas in our own galaxy, some tens of thousands of light-years away. Then, astronomer Edwin Hubble proved that these objects are galaxies in their own right, at distances of millions of light years. Today, astronomers can detect galaxies that are billions of light years away. Distances in the universe can be measured in all directions. As such, it is useful to consider distance as an absolute value function. In this section, we will continue our investigation of absolute value functions .

## Understanding Absolute Value

Recall that in its basic form [latex]\,f\left(x\right)=|x|,\,[/latex] the absolute value function is one of our toolkit functions. The absolute value function is commonly thought of as providing the distance the number is from zero on a number line. Algebraically, for whatever the input value is, the output is the value without regard to sign. Knowing this, we can use absolute value functions to solve some kinds of real-world problems.

## Absolute Value Function

The absolute value function can be defined as a piecewise function:

## Using Absolute Value to Determine Resistance

Electrical parts, such as resistors and capacitors, come with specified values of their operating parameters: resistance, capacitance, etc. However, due to imprecision in manufacturing, the actual values of these parameters vary somewhat from piece to piece, even when they are supposed to be the same. The best that manufacturers can do is to try to guarantee that the variations will stay within a specified range, often[latex]\,\text{±1%,}\,±\text{5%,}\,[/latex]or[latex]\,±\text{10%}\text{.}[/latex]

Suppose we have a resistor rated at 680 ohms,[latex]\,±\text{5%}\,[/latex]. Use the absolute value function to express the range of possible values of the actual resistance.

We can find that 5% of 680 ohms is 34 ohms. The absolute value of the difference between the actual and nominal resistance should not exceed the stated variability, so with the resistance [latex]\,R\,[/latex] in ohms,

Students who score within 20 points of 80 will pass a test. Write this as a distance from 80 using absolute value notation.

Using the variable[latex]\,p\,[/latex] for passing, [latex]\,|p-80|\le 20[/latex]

## Graphing an Absolute Value Function

The most significant feature of the absolute value graph is the corner point at which the graph changes direction. This point is shown at the origin in Figure 2.

Figure 3 shows the graph of [latex]\,y=2|x–3|+4.\,[/latex] The graph of [latex]\,y=|x|\,[/latex] has been shifted right 3 units, vertically stretched by a factor of 2, and shifted up 4 units. This means that the corner point is located at [latex]\,\left(3,4\right)\,[/latex] for this transformed function.

## Writing an Equation for an Absolute Value Function Given a Graph

Write an equation for the function graphed in Figure 4.

The basic absolute value function changes direction at the origin, so this graph has been shifted to the right 3 units and down 2 units from the basic toolkit function. See Figure 5.

We also notice that the graph appears vertically stretched because the width of the final graph on a horizontal line is not equal to 2 times the vertical distance from the corner to this line, as it would be for an unstretched absolute value function. Instead, the width is equal to 1 times the vertical distance, as shown in Figure 6.

From this information, we can write the equation

Note that these equations are algebraically equivalent—the stretch for an absolute value function can be written interchangeably as a vertical or horizontal stretch or compression.

If we couldn’t observe the stretch of the function from the graphs, could we algebraically determine it?

Yes. If we are unable to determine the stretch based on the width of the graph, we can solve for the stretch factor by putting in a known pair of values for [latex]\,x\,[/latex] and [latex]\,f\left(x\right).[/latex]

Now substituting in the point (1, 2)

Write the equation for the absolute value function that is horizontally shifted left 2 units, vertically flipped, and vertically shifted up 3 units.

[latex]f\left(x\right)=-|x+2|+3[/latex]

Do the graphs of absolute value functions always intersect the vertical axis? The horizontal axis?

Yes, they always intersect the vertical axis. The graph of an absolute value function will intersect the vertical axis when the input is zero.

No, they do not always intersect the horizontal axis. The graph may or may not intersect the horizontal axis, depending on how the graph has been shifted and reflected. It is possible for the absolute value function to intersect the horizontal axis at zero, one, or two points (see Figure 7).

Access these online resources for additional instruction and practice with graphing absolute value equations.

## Solving an Absolute Value Equation

In Other Type of Equations , we touched on the concepts of absolute value equations. Now that we understand a little more about their graphs, we can take another look at these types of equations. Now that we can graph an absolute value function, we will learn how to solve an absolute value equation. To solve an equation such as [latex]\,8=|2x-6|,\,[/latex] we notice that the absolute value will be equal to 8 if the quantity inside the absolute value is 8 or -8. This leads to two different equations we can solve independently.

Knowing how to solve problems involving absolute value functions is useful. For example, we may need to identify numbers or points on a line that are at a specified distance from a given reference point.

An absolute value equation is an equation in which the unknown variable appears in absolute value bars. For example,

## Solutions to Absolute Value Equations

For real numbers [latex]A[/latex] and [latex]B[/latex], an equation of the form [latex]|A|=B,[/latex] with [latex]B\ge 0,[/latex] will have solutions when [latex]A=B[/latex] or [latex]A=-B.[/latex] If B<0 , the equation [latex]|A|=B[/latex] has no solution.

Given the formula for an absolute value function, find the horizontal intercepts of its graph .

- Isolate the absolute value term.
- Use [latex]\,|A|=B\,[/latex] to write [latex]\,A=B\,[/latex] or [latex]\,\mathrm{-A}=B,\,[/latex] assuming [latex]\,B>0.[/latex]
- Solve for [latex]\,x.\,[/latex]

## Finding the Zeros of an Absolute Value Function

For the function[latex]\,f\left(x\right)=|4x+1|-7,[/latex] find the values of[latex]\,x\,[/latex]such that[latex]\,f\left(x\right)=0.[/latex]

The function outputs 0 when[latex]\,x=\frac{3}{2}\,[/latex]or[latex]\,x=-2.[/latex] See Figure 8.

For the function [latex]\,f\left(x\right)=|2x-1|-3,[/latex] find the values of [latex]\,x\,[/latex] such that [latex]\,f\left(x\right)=0.[/latex]

[latex]x=-1\,[/latex] or [latex]\,\,x=2[/latex]

Should we always expect two answers when solving[latex]\,|A|=B?[/latex]

No. We may find one, two, or even no answers. For example, there is no solution to [latex]\,2+|3x-5|=1.[/latex]

## Key Concepts

- Applied problems, such as ranges of possible values, can also be solved using the absolute value function.
- The graph of the absolute value function resembles a letter V. It has a corner point at which the graph changes direction.
- In an absolute value equation, an unknown variable is the input of an absolute value function.
- If the absolute value of an expression is set equal to a positive number, expect two solutions for the unknown variable.

## Section Exercises

- How do you solve an absolute value equation?

Isolate the absolute value term so that the equation is of the form[latex]\,|A|=B.\,[/latex]Form one equation by setting the expression inside the absolute value symbol,[latex]\,A,\,[/latex]equal to the expression on the other side of the equation,[latex]\,B.\,[/latex]Form a second equation by setting[latex]\,A\,[/latex]equal to the opposite of the expression on the other side of the equation,[latex]\,-B.\,[/latex]Solve each equation for the variable.

- How can you tell whether an absolute value function has two x -intercepts without graphing the function?
- When solving an absolute value function, the isolated absolute value term is equal to a negative number. What does that tell you about the graph of the absolute value function?

The graph of the absolute value function does not cross the[latex]\,x[/latex]-axis, so the graph is either completely above or completely below the[latex]\,x[/latex]-axis.

- How can you use the graph of an absolute value function to determine the x -values for which the function values are negative?
- Describe all numbers[latex]\,x\,[/latex]that are at a distance of[latex]\,\frac{1}{2}\,[/latex]from the number −4. Express this set of numbers using absolute value notation.

[latex]\,|x+4|=\frac{1}{2}\,[/latex]

- Describe the situation in which the distance that point[latex]\,x\,[/latex]is from 10 is at least 15 units. Express this set of numbers using absolute value notation.
- Find all function values[latex]\,f\left(x\right)\,[/latex]such that the distance from[latex]\,f\left(x\right)\,[/latex]to the value 8 is less than 0.03 units. Express this set of numbers using absolute value notation.

[latex]|f\left(x\right)-8|[/latex] <0.03

For the following exercises, find the x – and y -intercepts of the graphs of each function.

- [latex]f\left(x\right)=4|x-3|+4[/latex]
- [latex]f\left(x\right)=-3|x-2|-1[/latex]

[latex]\left(0,-7\right);\,[/latex]no[latex]\,x[/latex]-intercepts

- [latex]f\left(x\right)=-2|x+1|+6[/latex]
- [latex]f\left(x\right)=-5|x+2|+15[/latex]

[latex]\left(0,\,5\right),\left(1,0\right),\left(-5,0\right)[/latex]

- [latex]f\left(x\right)=2|x-1|-6[/latex]
- [latex]f\left(x\right)=|-2x+1|-13[/latex]

[latex]\left(0,-12\right),\left(-6,0\right),\left(7,0\right)[/latex]

- [latex]f\left(x\right)=-|x-9|+16[/latex]

For the following exercises, graph the absolute value function. Plot at least five points by hand for each graph.

- [latex]y=|x-1|[/latex]

- [latex]y=|x+1|[/latex]
- [latex]y=|x|+1[/latex]

For the following exercises, graph the given functions by hand.

- [latex]y=|x|-2[/latex]
- [latex]y=-|x|[/latex]

- [latex]y=-|x|-2[/latex]
- [latex]y=-|x-3|-2[/latex]

- [latex]f\left(x\right)=-|x-1|-2[/latex]
- [latex]f\left(x\right)=-|x+3|+4[/latex]

- [latex]f\left(x\right)=2|x+3|+1[/latex]
- [latex]f\left(x\right)=3|x-2|+3[/latex]

- [latex]f\left(x\right)=|2x-4|-3[/latex]
- [latex]f\left(x\right)=|3x+9|+2[/latex]

- [latex]f\left(x\right)=-|x-1|-3[/latex]
- [latex]f\left(x\right)=-|x+4|-3[/latex]

- [latex]f\left(x\right)=\frac{1}{2}|x+4|-3[/latex]
- Use a graphing utility to graph [latex]f\left(x\right)=10|x-2|[/latex] on the viewing window [latex]\left[0,4\right].[/latex] Identify the corresponding range. Show the graph.

range:[latex]\,\left[0,20\right][/latex]

- Use a graphing utility to graph[latex]\,f\left(x\right)=-100|x|+100\,[/latex]on the viewing window[latex]\,\left[-5,5\right].\,[/latex]Identify the corresponding range. Show the graph.

For the following exercises, graph each function using a graphing utility. Specify the viewing window.

- [latex]f\left(x\right)=-0.1|0.1\left(0.2-x\right)|+0.3[/latex]

[latex]x\text{-}[/latex]intercepts:

- [latex]f\left(x\right)=4×{10}^{9}|x-\left(5×{10}^{9}\right)|+2×{10}^{9}[/latex]

For the following exercises, solve the inequality.

- If possible, find all values of[latex]\,a\,[/latex]such that there are no [latex]\,y[/latex]-intercepts for[latex]\,f\left(x\right)=2|x+1|+a.[/latex]

There is no solution for[latex]\,a\,[/latex]that will keep the function from having a[latex]\,y[/latex]-intercept. The absolute value function always crosses the [latex]\,y[/latex]-intercept when[latex]\,x=0.[/latex]

- If possible, find all values of [latex]a[/latex] such that there are no [latex]x\text{-}[/latex]intercepts for [latex]f\left(x\right)=2|x+1|+a.[/latex]

## Real-World Applications

- The true proportion[latex]\,p\,[/latex]of people who give a favorable rating to Congress is 8% with a margin of error of 1.5%. Describe this statement using an absolute value equation.

[latex]|p-0.08|\le 0.015[/latex]

- Students who score within 18 points of the number 82 will pass a particular test. Write this statement using absolute value notation and use the variable[latex]\,x\,[/latex]for the score.
- A machinist must produce a bearing that is within 0.01 inches of the correct diameter of 5.0 inches. Using[latex]\,x\,[/latex]as the diameter of the bearing, write this statement using absolute value notation.

[latex]|x-5.0|\le 0.01[/latex]

- The tolerance for a ball bearing is 0.01. If the true diameter of the bearing is to be 2.0 inches and the measured value of the diameter is[latex]\,x\,[/latex]inches, express the tolerance using absolute value notation.

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## Absolute Value Equation and Function Worksheets

Explore this ensemble of printable absolute value equations and functions worksheets to hone the skills of high school students in evaluating absolute functions with input and output table, evaluating absolute value expressions, solving absolute value equations and graphing functions. Give a head-start to your practice with the free worksheets here.

## Solving Absolute Value Expression

Input and Output Tables

Using the input values and the rule, find out the output values of the absolute value function.

Input and Output Tables: Easy

Input and Output Tables: Moderate

Input and Output Tables: Difficult

- Download All

Evaluate Absolute Value Expression

Find the value of each absolute value expression for the particular value of x.

Evaluate Absolute Value: Easy

Evaluate Absolute Value: Moderate

Evaluate Absolute Value: Difficult

## Solving Absolute Value Equation

Existence of the Solution:

Supply this set of printable handouts to high school students and knock their skills into shape! They need to check if a given equation has a solution or not.

Sheet 1 | Sheet 2 | Grab 'em All

Type 1: | x | = a

Solve the absolute value equation and find the solutions. The question either has two solutions or no solution.

Type 2: |x + a| = b

Set x + a = b and x + a = -b, and solve the absolute value equations.

Easy: Sheet 1 | Sheet 2 | Grab 'em All

Moderate: Sheet 1 | Sheet 2 | Grab 'em All

Type 3: a |bx + c| = d

Isolate the absolute value expression and then solve.

Type 4: a |bx + c| + d = e

Isolate the absolute value expression from the constant term and solve for x.

Type 5: |ax + b| = |cx + d|

All you need to do in this pdf practice set is this: find the break points, set the interval, solve for x and check for an extraneous solution.

Graphing Absolute Value Function

Identify the Absolute Value Function

The graph of the absolute value functions includes vertical shift, horizontal shift and reflection. Identify the absolute value function in each graph.

Difficult: Sheet 1 | Sheet 2 | Grab 'em All

Each question in this set of pdf worksheets contains a function and a grid displaying the x and y coordinates below. Identify the transformations involved in the function and then graph.

Vertical / Horizontal shift:

Graphing Functions: Easy 1

Graphing Functions: Easy 2 | Grab 'em All

Vertical shift + Horizontal shift:

Graphing Functions: Moderate 1

Graphing Functions: Moderate 2 | Grab 'em All

Vertical shift + Horizontal shift + Reflection:

Graphing Functions: Difficult 1

Graphing Functions: Difficult 2 | Grab 'em All

Related Worksheets

» One-step Equation

» Two-step Equation

» Multi-step Equation

» Quadratic Equation

» Equations

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## Graphing Absolute Value Functions

How to graph absolute value functions.

This lesson is about graphing an absolute value function when the expression inside the absolute value symbol is linear. It is linear if the variable “[latex]x[/latex]” has a power of [latex]1[/latex]. The graph of absolute value function has a shape of “V” or inverted “V”.

## Absolute Value Function in Equation Form

The general form of an absolute value function that is linear is

- where the vertex (low or high point) is located at

- the vertical line

divides the graph into two equal halves

## KEY POINTS TO REMEMBER:

- The specific approach that we are going to use is to find the “right amount of points” that can be plotted on the [latex]xy[/latex]-axis so that we have a good approximation on how the graph of the absolute value function looks likes.
- Don’t fall into the common trap to always use [latex]x = 0[/latex] as the middle value of the [latex]x[/latex] coordinates. This may work at times, but this idea is not so reliable.
- I suggest using the [latex]x[/latex]-coordinate of the vertex, [latex]\left( {{{ – b} \over m},\,c} \right)[/latex], which is [latex]x = {{ – b} \over m}[/latex] as the middle value of all [latex]x[/latex]-values in the table.
- In other words, once you have determined what the middle value for [latex]x[/latex] is, then go ahead and pick any arbitrary [latex]x[/latex] values to the left and right of it as long as it is properly spaced out.

Again, the best way to illustrate this simple idea is through the use of examples!

## Examples of Graphing Absolute Value Functions

Example 1: Graph the absolute value function below using the table of values.

This is the most basic form of an absolute value function. If you see that the only expression inside the absolute value symbol is just “[latex]x[/latex]”, assume that the vertex of the graph will occur when [latex]x = 0[/latex].

Or, if you want to use the formula above to find the vertex, rewrite the given function in the standard form so that you can identify the values of [latex]m[/latex], [latex]b[/latex], and [latex]c[/latex].

The vertex is calculated as

Since [latex]x = 0[/latex], this becomes the center values of all [latex]x[/latex]’s. Now we can pick some numbers to the left and to the right of zero. I would suggest using equal amount of numbers that are of the same increment.

Pick [latex]-3[/latex], [latex]-2[/latex], [latex]-1[/latex] to the left of zero, and [latex]+1[/latex], [latex]+2[/latex], [latex]+3[/latex] to its right. Evaluate all values of [latex]x[/latex] into the function [latex]y = \left| x \right|[/latex] to get the corresponding [latex]y[/latex]-values.

Notice that the graph has a low point determined by the middle [latex]x[/latex]-value which is the [latex]x[/latex]-coordinate of the vertex itself, i.e. ( 0 ,0).

Example 2: Graph the absolute value function below using the table of values.

The first step is to find the [latex]x[/latex]-coordinate of the vertex which will serve as the center point in the table of values of [latex]x[/latex].

Rewrite [latex]y = \left| {x – 2} \right|\,\,\,[/latex]as [latex]y = \left| {1x + \left( { – 2} \right)} \right| + 0[/latex] where [latex] m = 1[/latex], [latex]b = -2[/latex], and [latex]c = 0[/latex]. We calculate the vertex as…

The [latex]x[/latex]-coordinate of the vertex will be the center value of all [latex]x[/latex]’s on the table. We generated the rest of the [latex]x[/latex] by finding three numbers to the left and right of the middle value of [latex]2[/latex] with an increment of [latex]1[/latex]. You may use an increment of [latex]2[/latex], and trust me, the graph will be the same.

Plot the points on the [latex]xy[/latex]-plane and connect the dots with a straight edge. If you get it right, you should have something similar below. As you can see, the low point of the graph is the vertex located at ([latex]2[/latex],[latex]0[/latex]).

Example 3: Graph the absolute value function below using the table of values.

I hope you start realizing that the first step is to always express the given absolute value function in standard form. This allows us to identify the correct values of [latex]m[/latex], [latex]b[/latex], and [latex]c[/latex] which we will use to substitute into the formula.

Clearly, the required values are [latex]m = 2[/latex], [latex]b = 6[/latex], and [latex]c = -4[/latex].

Then we calculate the vertex as follows;

Our table of values will have a center value of [latex]x = – 3[/latex]. Generate 3 numbers both to the left and right of [latex]x = – 3[/latex] with an increment of [latex]1[/latex]. Then evaluate each value of [latex]x[/latex] into the function [latex]y = \left| {\,2x + 6\,} \right| – 4\,[/latex] to get the corresponding values of [latex]y[/latex] in the table.

Your table should look something like this

Plot the points on the Cartesian plane and connect them using a straight edge such as a ruler.

Example 4: Graph the absolute value function below using the table of values.

This is an example of an absolute value function whose graph is an inverted “V”. This happens because the coefficient of the absolute value symbol is negative, that is, [latex] – 1[/latex].

Let’s rewrite this in the standard form.

That means [latex]m = 1[/latex], [latex]b = -3[/latex], and [latex]c = -2[/latex].

Solving the vertex of the function,

The table of values will have a center value of [latex]x = 3[/latex].

Plotting the points in the [latex]xy[/latex]-axis,

You may also be interested in these related math lessons or tutorials:

Solving Absolute Value Equations Solving Absolute Value Inequalities

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## 1.9: Absolute Value Functions

- Last updated
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- Page ID 59844

- David Arnold
- College of the Redwoods
- 1.9.1: Piecewise-Defined Functions In preparation for the definition of the absolute value function, it is extremely important to have a good grasp of the concept of a piecewise-defined function.
- 1.9.2: Absolute Value The absolute value of a number is a measure of its magnitude, sans (without) its sign.
- 1.9.3: Absolute Value Equations
- 1.9.4: Absolute Value Inequalities

Thumbnail: The graph of the absolute value function for real numbers. (CC BY-SA 3.0; Qef and Ævar Arnfjörð Bjarmason via Wikipedia).

## IMAGES

## VIDEO

## COMMENTS

Sample Response: The absolute value function is symmetric with its vertex on the line of symmetry. Because the points (-6, -2) and (0, -2) have the same output, the points are the same distance from the line of symmetry. Midway between -6 and 0 is the value of -3.

Study with Quizlet and memorize flashcards containing terms like Which of the following is the graph of f(x)= |x| translated 2 units right, 2 units up, and dilated by a factor of 1/3?, What is the vertex of f(x) = |x + 8| - 3?, Which function is a translation of the parent absolute value function? and more.

Recall that in its basic form f (x) = | x |, f (x) = | x |, the absolute value function is one of our toolkit functions. The absolute value function is commonly thought of as providing the distance the number is from zero on a number line. Algebraically, for whatever the input value is, the output is the value without regard to sign. Knowing ...

Definition: Absolute Value Function. The absolute value function can be defined as. f(x) = |x| = { x if x ≥ 0 − x if x < 0. The absolute value function is commonly used to determine the distance between two numbers on the number line. Given two values a and b, then |a − b| will give the distance, a positive quantity, between these values ...

The absolute value function is commonly thought of as providing the distance the number is from zero on a number line. Algebraically, for whatever the input value is, the output is the value without regard to sign. Absolute Value Function. The absolute value function can be defined as a piecewise function.

The general form of an absolute value function is f (x)=a|x-h|+k. From this form, we can draw graphs. This article reviews how to draw the graphs of absolute value functions. General form of an absolute value equation: f ( x) = a | x − h | + k. The variable a tells us how far the graph stretches vertically, and whether the graph opens up or ...

3.5: Absolute Value Functions. There are a few ways to describe what is meant by the absolute value | x | of a real number x. You may have been taught that | x | is the distance from the real number x to 0 on the number line. So, for example, | 5 | = 5 and | − 5 | = 5, since each is 5 units from 0 on the number line.

To solve absolute value equations, find x values that make the expression inside the absolute value positive or negative the constant. To graph absolute value functions, plot two lines for the positive and negative cases that meet at the expression's zero. The graph is v-shaped. Created by Sal Khan and CK-12 Foundation.

The standard absolute value graph y=|x| has its vertex at (0, 0). If you want to change the point to be at (3,0), that means you are making x=3. Notice, these are on opposite sides of the "=". if you need to place them on the same side of the "=", then you would have x-3=0.

Use the transformations on the function f (x) = x| to select the correct graph of f (x)= 1/3 IxI+1. Obtuse angel on (0,1) / B. Choose the function that represents the graph of the transformation of f (x) = |x| that opens down and has a vertex of (3,2) f (x) = -|x - 3| + 2. Identify the function that contains the data in the following table:

Recall that in its basic form f (x) = |x|, f ( x) = | x |, the absolute value function is one of our toolkit functions. The absolute value function is commonly thought of as providing the distance the number is from zero on a number line. Algebraically, for whatever the input value is, the output is the value without regard to sign.

To solve an equation such as 8 = |2x − 6|, we notice that the absolute value will be equal to 8 if the quantity inside the absolute value is 8 or -8. This leads to two different equations we can solve independently. 2x − 6 = 8 or 2x − 6 = −8 2x = 14 2x = −2 x = 7 x = −1. Knowing how to solve problems involving absolute value ...

Explore this ensemble of printable absolute value equations and functions worksheets to hone the skills of high school students in evaluating absolute functions with input and output table, evaluating absolute value expressions, solving absolute value equations and graphing functions. Give a head-start to your practice with the free worksheets ...

Example 1: Graph the absolute value function below using the table of values. This is the most basic form of an absolute value function. If you see that the only expression inside the absolute value symbol is just " [latex]x [/latex]", assume that the vertex of the graph will occur when [latex]x = 0 [/latex]. Or, if you want to use the ...

Graph absolute value functions. Graph g ( x) = − 5 | x + 2 | + 2 . Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.

Skill plans. IXL plans. Washington state standards. Textbooks. Test prep. Improve your math knowledge with free questions in "Graph an absolute value function" and thousands of other math skills.

Study with Quizlet and memorize flashcards containing terms like The standard form of an absolute value function is mc002-1.jpg. Which of the following represents the vertex?, Which of the following is the graph of f(x) = |x| translated 2 units right, 2 units up, and dilated by a factor of mc018-1.jpg?, What is the range of the absolute value function below? mc009-1.jpg and more.

For problems 1 - 10 solve each of the equation. For problems 11 - 13 find all the real valued solutions to the equation. Here is a set of assignement problems (for use by instructors) to accompany the Absolute Value Equations section of the Solving Equations and Inequalities chapter of the notes for Paul Dawkins Algebra course at Lamar ...

Now, if you think about it we can do this for any positive number, not just 4. So, this leads to the following general formula for equations involving absolute value. If |p| = b, b > 0 then p = −b or p =b If | p | = b, b > 0 then p = − b or p = b. Notice that this does require the b b be a positive number.

1.9.1: Piecewise-Defined Functions In preparation for the definition of the absolute value function, it is extremely important to have a good grasp of the concept of a piecewise-defined function. 1.9.2: Absolute Value The absolute value of a number is a measure of its magnitude, sans (without) its sign. 1.9.3: Absolute Value Equations

Quiz 1. Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.

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The Square Root Function / Assignment. 5 terms. Ryman6969. Preview. Overview of 1st Semester Pre-Calculus Equations. 142 terms. cgs800023. Preview. Calc Test 2 Study Set. 22 terms. Serena_Squires. ... Which absolute value function has a graph that is wider than the parent function, f(x) = |x|, and is translated to the right 2 units?