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Solution - Absolute value equations

Exact form: x=-32,14
x=-\frac{3}{2} , \frac{1}{4}
Mixed number form: x=-112,14
x=-1\frac{1}{2} , \frac{1}{4}
Decimal form: x=1.5,0.25
x=-1.5 , 0.25

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
|x2|=|3x+1|
without the absolute value bars:

|x|=|y||x2|=|3x+1|
x=+y(x2)=(3x+1)
x=y(x2)=(3x+1)
+x=y(x2)=(3x+1)
x=y(x2)=(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||x2|=|3x+1|
x=+y , +x=y(x2)=(3x+1)
x=y , x=y(x2)=(3x+1)

2. Solve the two equations for x

11 additional steps

(x-2)=(3x+1)

Subtract from both sides:

(x-2)-3x=(3x+1)-3x

Group like terms:

(x-3x)-2=(3x+1)-3x

Simplify the arithmetic:

-2x-2=(3x+1)-3x

Group like terms:

-2x-2=(3x-3x)+1

Simplify the arithmetic:

2x2=1

Add to both sides:

(-2x-2)+2=1+2

Simplify the arithmetic:

2x=1+2

Simplify the arithmetic:

2x=3

Divide both sides by :

(-2x)-2=3-2

Cancel out the negatives:

2x2=3-2

Simplify the fraction:

x=3-2

Move the negative sign from the denominator to the numerator:

x=-32

10 additional steps

(x-2)=-(3x+1)

Expand the parentheses:

(x-2)=-3x-1

Add to both sides:

(x-2)+3x=(-3x-1)+3x

Group like terms:

(x+3x)-2=(-3x-1)+3x

Simplify the arithmetic:

4x-2=(-3x-1)+3x

Group like terms:

4x-2=(-3x+3x)-1

Simplify the arithmetic:

4x2=1

Add to both sides:

(4x-2)+2=-1+2

Simplify the arithmetic:

4x=1+2

Simplify the arithmetic:

4x=1

Divide both sides by :

(4x)4=14

Simplify the fraction:

x=14

3. List the solutions

x=-32,14
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|x2|
y=|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.