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Solution - Absolute value equations

Exact form: x=1,7
x=1 , -7

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
|4x+4|=|2x+10|
without the absolute value bars:

|x|=|y||4x+4|=|2x+10|
x=+y(4x+4)=(2x+10)
x=y(4x+4)=(2x+10)
+x=y(4x+4)=(2x+10)
x=y(4x+4)=(2x+10)

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||4x+4|=|2x+10|
x=+y , +x=y(4x+4)=(2x+10)
x=y , x=y(4x+4)=(2x+10)

2. Solve the two equations for x

10 additional steps

(4x+4)=(-2x+10)

Add to both sides:

(4x+4)+2x=(-2x+10)+2x

Group like terms:

(4x+2x)+4=(-2x+10)+2x

Simplify the arithmetic:

6x+4=(-2x+10)+2x

Group like terms:

6x+4=(-2x+2x)+10

Simplify the arithmetic:

6x+4=10

Subtract from both sides:

(6x+4)-4=10-4

Simplify the arithmetic:

6x=104

Simplify the arithmetic:

6x=6

Divide both sides by :

(6x)6=66

Simplify the fraction:

x=66

Simplify the fraction:

x=1

12 additional steps

(4x+4)=-(-2x+10)

Expand the parentheses:

(4x+4)=2x-10

Subtract from both sides:

(4x+4)-2x=(2x-10)-2x

Group like terms:

(4x-2x)+4=(2x-10)-2x

Simplify the arithmetic:

2x+4=(2x-10)-2x

Group like terms:

2x+4=(2x-2x)-10

Simplify the arithmetic:

2x+4=10

Subtract from both sides:

(2x+4)-4=-10-4

Simplify the arithmetic:

2x=104

Simplify the arithmetic:

2x=14

Divide both sides by :

(2x)2=-142

Simplify the fraction:

x=-142

Find the greatest common factor of the numerator and denominator:

x=(-7·2)(1·2)

Factor out and cancel the greatest common factor:

x=7

3. List the solutions

x=1,7
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|4x+4|
y=|2x+10|
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.