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Solution - Absolute value equations

Exact form: x=-3,-12
x=-3 , -\frac{1}{2}
Decimal form: x=3,0.5
x=-3 , -0.5

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+4|=|x2|
without the absolute value bars:

|x|=|y||3x+4|=|x2|
x=+y(3x+4)=(x2)
x=y(3x+4)=(x2)
+x=y(3x+4)=(x2)
x=y(3x+4)=(x2)

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+4|=|x2|
x=+y , +x=y(3x+4)=(x2)
x=y , x=y(3x+4)=(x2)

2. Solve the two equations for x

11 additional steps

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

Subtract from both sides:

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

Group like terms:

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

Simplify the arithmetic:

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

Group like terms:

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

Simplify the arithmetic:

2x+4=2

Subtract from both sides:

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

Simplify the arithmetic:

2x=24

Simplify the arithmetic:

2x=6

Divide both sides by :

(2x)2=-62

Simplify the fraction:

x=-62

Find the greatest common factor of the numerator and denominator:

x=(-3·2)(1·2)

Factor out and cancel the greatest common factor:

x=3

12 additional steps

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

Expand the parentheses:

(3x+4)=-x+2

Add to both sides:

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

Group like terms:

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

Simplify the arithmetic:

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

Group like terms:

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

Simplify the arithmetic:

4x+4=2

Subtract from both sides:

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

Simplify the arithmetic:

4x=24

Simplify the arithmetic:

4x=2

Divide both sides by :

(4x)4=-24

Simplify the fraction:

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

3. List the solutions

x=-3,-12
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|3x+4|
y=|x2|
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.