Solve for the variable in the equation:

### Watch This

Khan Academy Absolute Value Equations

### Guidance

Recall that a linear equation relates mathematical expressions with an equals sign. To solve an absolute linear equation you have to remember the same rules that you have used to solve linear equations with one variable. The difference with absolute value equations is there will often be two solutions instead of just one solution. Consider the following equations:

1.

This means that
*
x
*
can be 5 or
*
x
*
can be –5. This is because
.

2.

This means that can be 7 or can be –7. This is because .

3.

The absolute value of can never be equal to a negative number. Therefore if an absolute value equation is equal to a negative number, there is no solution.

#### Example A

**
Solution:
**
Set up two equations to solve. You know that either
OR
.
*
The quantity inside the absolute value signs could be either the positive or negative of the value on the right side.
*

Solutions

#### Example B

**
Solution:
**
First of all, you know that
. Now, set up two equations to solve. You know that either
OR
.

Solutions

#### Example C

**
Solution:
**
First of all, you know that
. Now, set up two equations to solve. You know that either
OR
.

Solutions

#### Concept Problem Revisited

Solve for the variable in the expression:

Because
, the expression
is equal to 4
**
or
**
–4.

Just like with regular linear equations, you can check both answers.

### Guided Practice

Solve each equation.

1.

2.

3.

**
Answers:
**

1. The solutions are . Here are the steps:

2. The solutions are . First, isolate the part of the equation with the absolute value sign by adding 3 to both sides. The new equation is . Then, set up two equations and solve.

3. The solutions are . Here are the steps to solve:

### Explore More

Solve each of the following absolute value linear equations.