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Solution - Absolute value equations

Exact form: x=13,-5
x=\frac{1}{3} , -5
Decimal form: x=0.333,5
x=0.333 , -5

Other Ways to Solve

Absolute value equations

Step-by-step explanation

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

|x3|+2|x+1|=0

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

|x3|+2|x+1|2|x+1|=2|x+1|

Simplify the arithmetic

|x3|=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
|x3|=2|x+1|
without the absolute value bars:

|x|=|y||x3|=2|x+1|
x=+y(x3)=2(x+1)
x=y(x3)=2((x+1))
+x=y(x3)=2(x+1)
x=y(x3)=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||x3|=2|x+1|
x=+y , +x=y(x3)=2(x+1)
x=y , x=y(x3)=2((x+1))

3. Solve the two equations for x

11 additional steps

(x-3)=-2·(x+1)

Expand the parentheses:

(x-3)=-2x-2·1

Simplify the arithmetic:

(x-3)=-2x-2

Add to both sides:

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

Group like terms:

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

Simplify the arithmetic:

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

Group like terms:

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

Simplify the arithmetic:

3x3=2

Add to both sides:

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

Simplify the arithmetic:

3x=2+3

Simplify the arithmetic:

3x=1

Divide both sides by :

(3x)3=13

Simplify the fraction:

x=13

15 additional steps

(x-3)=-2·(-(x+1))

Expand the parentheses:

(x-3)=-2·(-x-1)

(x-3)=-2·-x-2·-1

Group like terms:

(x-3)=(-2·-1)x-2·-1

Multiply the coefficients:

(x-3)=2x-2·-1

Simplify the arithmetic:

(x-3)=2x+2

Subtract from both sides:

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

Group like terms:

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

Simplify the arithmetic:

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

Group like terms:

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

Simplify the arithmetic:

x3=2

Add to both sides:

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

Simplify the arithmetic:

x=2+3

Simplify the arithmetic:

x=5

Multiply both sides by :

-x·-1=5·-1

Remove the one(s):

x=5·-1

Simplify the arithmetic:

x=5

4. List the solutions

x=13,-5
(2 solution(s))

5. Graph

Each line represents the function of one side of the equation:
y=|x3|
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.