Enter an equation or problem
Camera input is not recognized!

Solution - Absolute value equations

Exact form: x=-12,-6
x=-\frac{1}{2} , -6
Decimal form: x=0.5,6
x=-0.5 , -6

Other Ways to Solve

Absolute value equations

Step-by-step explanation

1. Rewrite the equation without absolute value bars

Use the rules:
|x|=|y|x=±y and |x|=|y|±x=y
to write all four options of the equation
|x+5|=|3x+7|
without the absolute value bars:

|x|=|y||x+5|=|3x+7|
x=+y(x+5)=(3x+7)
x=y(x+5)=(3x+7)
+x=y(x+5)=(3x+7)
x=y(x+5)=(3x+7)

When simplified, equations x=+y and +x=y are the same and equations x=y and x=y are the same, so we end up with only 2 equations:

|x|=|y||x+5|=|3x+7|
x=+y , +x=y(x+5)=(3x+7)
x=y , x=y(x+5)=(3x+7)

2. Solve the two equations for x

13 additional steps

(-x+5)=(3x+7)

Subtract from both sides:

(-x+5)-3x=(3x+7)-3x

Group like terms:

(-x-3x)+5=(3x+7)-3x

Simplify the arithmetic:

-4x+5=(3x+7)-3x

Group like terms:

-4x+5=(3x-3x)+7

Simplify the arithmetic:

4x+5=7

Subtract from both sides:

(-4x+5)-5=7-5

Simplify the arithmetic:

4x=75

Simplify the arithmetic:

4x=2

Divide both sides by :

(-4x)-4=2-4

Cancel out the negatives:

4x4=2-4

Simplify the fraction:

x=2-4

Move the negative sign from the denominator to the numerator:

x=-24

Find the greatest common factor of the numerator and denominator:

x=(-1·2)(2·2)

Factor out and cancel the greatest common factor:

x=-12

12 additional steps

(-x+5)=-(3x+7)

Expand the parentheses:

(-x+5)=-3x-7

Add to both sides:

(-x+5)+3x=(-3x-7)+3x

Group like terms:

(-x+3x)+5=(-3x-7)+3x

Simplify the arithmetic:

2x+5=(-3x-7)+3x

Group like terms:

2x+5=(-3x+3x)-7

Simplify the arithmetic:

2x+5=7

Subtract from both sides:

(2x+5)-5=-7-5

Simplify the arithmetic:

2x=75

Simplify the arithmetic:

2x=12

Divide both sides by :

(2x)2=-122

Simplify the fraction:

x=-122

Find the greatest common factor of the numerator and denominator:

x=(-6·2)(1·2)

Factor out and cancel the greatest common factor:

x=6

3. List the solutions

x=-12,-6
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|x+5|
y=|3x+7|
The equation is true where the two lines cross.

Why learn this

We encounter absolute values almost daily. For example: If you walk 3 miles to school, do you also walk minus 3 miles when you go back home? The answer is no because distances use absolute value. The absolute value of the distance between home and school is 3 miles, there or back.
In short, absolute values help us deal with concepts like distance, ranges of possible values, and deviation from a set value.