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Solution - Absolute value equations

Exact form: x=314,716
x=\frac{3}{14} , \frac{7}{16}
Decimal form: x=0.214,0.438
x=0.214 , 0.438

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+2|=5|3x+1|
without the absolute value bars:

|x|=|y||x+2|=5|3x+1|
x=+y(x+2)=5(3x+1)
x=y(x+2)=5((3x+1))
+x=y(x+2)=5(3x+1)
x=y(x+2)=5(3x+1)

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+2|=5|3x+1|
x=+y , +x=y(x+2)=5(3x+1)
x=y , x=y(x+2)=5((3x+1))

2. Solve the two equations for x

12 additional steps

(-x+2)=5·(-3x+1)

Expand the parentheses:

(-x+2)=5·-3x+5·1

Multiply the coefficients:

(-x+2)=-15x+5·1

Simplify the arithmetic:

(-x+2)=-15x+5

Add to both sides:

(-x+2)+15x=(-15x+5)+15x

Group like terms:

(-x+15x)+2=(-15x+5)+15x

Simplify the arithmetic:

14x+2=(-15x+5)+15x

Group like terms:

14x+2=(-15x+15x)+5

Simplify the arithmetic:

14x+2=5

Subtract from both sides:

(14x+2)-2=5-2

Simplify the arithmetic:

14x=52

Simplify the arithmetic:

14x=3

Divide both sides by :

(14x)14=314

Simplify the fraction:

x=314

15 additional steps

(-x+2)=5·(-(-3x+1))

Expand the parentheses:

(-x+2)=5·(3x-1)

Expand the parentheses:

(-x+2)=5·3x+5·-1

Multiply the coefficients:

(-x+2)=15x+5·-1

Simplify the arithmetic:

(-x+2)=15x-5

Subtract from both sides:

(-x+2)-15x=(15x-5)-15x

Group like terms:

(-x-15x)+2=(15x-5)-15x

Simplify the arithmetic:

-16x+2=(15x-5)-15x

Group like terms:

-16x+2=(15x-15x)-5

Simplify the arithmetic:

16x+2=5

Subtract from both sides:

(-16x+2)-2=-5-2

Simplify the arithmetic:

16x=52

Simplify the arithmetic:

16x=7

Divide both sides by :

(-16x)-16=-7-16

Cancel out the negatives:

16x16=-7-16

Simplify the fraction:

x=-7-16

Cancel out the negatives:

x=716

3. List the solutions

x=314,716
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|x+2|
y=5|3x+1|
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.