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Solution - Absolute value equations

Exact form: x=-12,143
x=-\frac{1}{2} , \frac{14}{3}
Mixed number form: x=-12,423
x=-\frac{1}{2} , 4\frac{2}{3}
Decimal form: x=0.5,4.667
x=-0.5 , 4.667

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
|7x+12|=|x+16|
without the absolute value bars:

|x|=|y||7x+12|=|x+16|
x=+y(7x+12)=(x+16)
x=y(7x+12)=(x+16)
+x=y(7x+12)=(x+16)
x=y(7x+12)=(x+16)

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||7x+12|=|x+16|
x=+y , +x=y(7x+12)=(x+16)
x=y , x=y(7x+12)=(x+16)

2. Solve the two equations for x

13 additional steps

(-7x+12)=(x+16)

Subtract from both sides:

(-7x+12)-x=(x+16)-x

Group like terms:

(-7x-x)+12=(x+16)-x

Simplify the arithmetic:

-8x+12=(x+16)-x

Group like terms:

-8x+12=(x-x)+16

Simplify the arithmetic:

8x+12=16

Subtract from both sides:

(-8x+12)-12=16-12

Simplify the arithmetic:

8x=1612

Simplify the arithmetic:

8x=4

Divide both sides by :

(-8x)-8=4-8

Cancel out the negatives:

8x8=4-8

Simplify the fraction:

x=4-8

Move the negative sign from the denominator to the numerator:

x=-48

Find the greatest common factor of the numerator and denominator:

x=(-1·4)(2·4)

Factor out and cancel the greatest common factor:

x=-12

14 additional steps

(-7x+12)=-(x+16)

Expand the parentheses:

(-7x+12)=-x-16

Add to both sides:

(-7x+12)+x=(-x-16)+x

Group like terms:

(-7x+x)+12=(-x-16)+x

Simplify the arithmetic:

-6x+12=(-x-16)+x

Group like terms:

-6x+12=(-x+x)-16

Simplify the arithmetic:

6x+12=16

Subtract from both sides:

(-6x+12)-12=-16-12

Simplify the arithmetic:

6x=1612

Simplify the arithmetic:

6x=28

Divide both sides by :

(-6x)-6=-28-6

Cancel out the negatives:

6x6=-28-6

Simplify the fraction:

x=-28-6

Cancel out the negatives:

x=286

Find the greatest common factor of the numerator and denominator:

x=(14·2)(3·2)

Factor out and cancel the greatest common factor:

x=143

3. List the solutions

x=-12,143
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|7x+12|
y=|x+16|
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.