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Solution - Absolute value equations

Exact form: x=-8,-43
x=-8 , -\frac{4}{3}
Mixed number form: x=-8,-113
x=-8 , -1\frac{1}{3}
Decimal form: x=8,1.333
x=-8 , -1.333

Other Ways to Solve

Absolute value equations

Step-by-step explanation

1. Rewrite the equation with one absolute value terms on each side

|2x+4|+|4x+12|=0

Add |4x+12| to both sides of the equation:

|2x+4|+|4x+12||4x+12|=|4x+12|

Simplify the arithmetic

|2x+4|=|4x+12|

2. 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
|2x+4|=|4x+12|
without the absolute value bars:

|x|=|y||2x+4|=|4x+12|
x=+y(2x+4)=(4x+12)
x=y(2x+4)=(4x+12)
+x=y(2x+4)=(4x+12)
x=y(2x+4)=(4x+12)

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||2x+4|=|4x+12|
x=+y , +x=y(2x+4)=(4x+12)
x=y , x=y(2x+4)=(4x+12)

3. Solve the two equations for x

12 additional steps

(-2x+4)=-(4x+12)

Expand the parentheses:

(-2x+4)=-4x-12

Add to both sides:

(-2x+4)+4x=(-4x-12)+4x

Group like terms:

(-2x+4x)+4=(-4x-12)+4x

Simplify the arithmetic:

2x+4=(-4x-12)+4x

Group like terms:

2x+4=(-4x+4x)-12

Simplify the arithmetic:

2x+4=12

Subtract from both sides:

(2x+4)-4=-12-4

Simplify the arithmetic:

2x=124

Simplify the arithmetic:

2x=16

Divide both sides by :

(2x)2=-162

Simplify the fraction:

x=-162

Find the greatest common factor of the numerator and denominator:

x=(-8·2)(1·2)

Factor out and cancel the greatest common factor:

x=8

14 additional steps

(-2x+4)=-(-(4x+12))

NT_MSLUS_MAINSTEP_RESOLVE_DOUBLE_MINUS:

(-2x+4)=4x+12

Subtract from both sides:

(-2x+4)-4x=(4x+12)-4x

Group like terms:

(-2x-4x)+4=(4x+12)-4x

Simplify the arithmetic:

-6x+4=(4x+12)-4x

Group like terms:

-6x+4=(4x-4x)+12

Simplify the arithmetic:

6x+4=12

Subtract from both sides:

(-6x+4)-4=12-4

Simplify the arithmetic:

6x=124

Simplify the arithmetic:

6x=8

Divide both sides by :

(-6x)-6=8-6

Cancel out the negatives:

6x6=8-6

Simplify the fraction:

x=8-6

Move the negative sign from the denominator to the numerator:

x=-86

Find the greatest common factor of the numerator and denominator:

x=(-4·2)(3·2)

Factor out and cancel the greatest common factor:

x=-43

4. List the solutions

x=-8,-43
(2 solution(s))

5. Graph

Each line represents the function of one side of the equation:
y=|2x+4|
y=|4x+12|
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.