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Solution - Absolute value equations

Exact form: x=4,0
x=-4 , 0

Other Ways to Solve

Absolute value equations

Step-by-step explanation

1. Rewrite the equation with one absolute value terms on each side

|x2|2|x+1|=0

Add 2|x+1| to both sides of the equation:

|x2|2|x+1|+2|x+1|=2|x+1|

Simplify the arithmetic

|x2|=2|x+1|

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

|x|=|y||x2|=2|x+1|
x=+y(x2)=2(x+1)
x=y(x2)=2((x+1))
+x=y(x2)=2(x+1)
x=y(x2)=2(x+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|=2|x+1|
x=+y , +x=y(x2)=2(x+1)
x=y , x=y(x2)=2((x+1))

3. Solve the two equations for x

12 additional steps

(x-2)=2·(x+1)

Expand the parentheses:

(x-2)=2x+2·1

Simplify the arithmetic:

(x-2)=2x+2

Subtract from both sides:

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

Group like terms:

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

Simplify the arithmetic:

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

Group like terms:

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

Simplify the arithmetic:

x2=2

Add to both sides:

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

Simplify the arithmetic:

x=2+2

Simplify the arithmetic:

x=4

Multiply both sides by :

-x·-1=4·-1

Remove the one(s):

x=4·-1

Simplify the arithmetic:

x=4

13 additional steps

(x-2)=2·(-(x+1))

Expand the parentheses:

(x-2)=2·(-x-1)

(x-2)=2·-x+2·-1

Group like terms:

(x-2)=(2·-1)x+2·-1

Multiply the coefficients:

(x-2)=-2x+2·-1

Simplify the arithmetic:

(x-2)=-2x-2

Add to both sides:

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

Group like terms:

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

Simplify the arithmetic:

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

Group like terms:

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

Simplify the arithmetic:

3x2=2

Add to both sides:

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

Simplify the arithmetic:

3x=2+2

Simplify the arithmetic:

3x=0

Divide both sides by the coefficient:

x=0

4. List the solutions

x=4,0
(2 solution(s))

5. Graph

Each line represents the function of one side of the equation:
y=|x2|
y=2|x+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.