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Solution - Absolute value equations

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

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

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

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

2. Solve the two equations for x

12 additional steps

(-3x+2)=x

Subtract from both sides:

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

Group like terms:

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

Simplify the arithmetic:

4x+2=xx

Simplify the arithmetic:

4x+2=0

Subtract from both sides:

(-4x+2)-2=0-2

Simplify the arithmetic:

4x=02

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

Cancel out the negatives:

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

11 additional steps

(-3x+2)=-x

Add to both sides:

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

Group like terms:

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

Simplify the arithmetic:

2x+2=x+x

Simplify the arithmetic:

2x+2=0

Subtract from both sides:

(-2x+2)-2=0-2

Simplify the arithmetic:

2x=02

Simplify the arithmetic:

2x=2

Divide both sides by :

(-2x)-2=-2-2

Cancel out the negatives:

2x2=-2-2

Simplify the fraction:

x=-2-2

Cancel out the negatives:

x=22

Simplify the fraction:

x=1

3. List the solutions

x=12,1
(2 solution(s))

4. Graph

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