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Solution - Absolute value equations

Exact form: x=-4,-83
x=-4 , -\frac{8}{3}
Mixed number form: x=-4,-223
x=-4 , -2\frac{2}{3}
Decimal form: x=4,2.667
x=-4 , -2.667

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

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

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

2. Solve the two equations for x

12 additional steps

(x+2)=2·(x+3)

Expand the parentheses:

(x+2)=2x+2·3

Simplify the arithmetic:

(x+2)=2x+6

Subtract from both sides:

(x+2)-2x=(2x+6)-2x

Group like terms:

(x-2x)+2=(2x+6)-2x

Simplify the arithmetic:

-x+2=(2x+6)-2x

Group like terms:

-x+2=(2x-2x)+6

Simplify the arithmetic:

x+2=6

Subtract from both sides:

(-x+2)-2=6-2

Simplify the arithmetic:

x=62

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

14 additional steps

(x+2)=2·(-(x+3))

Expand the parentheses:

(x+2)=2·(-x-3)

(x+2)=2·-x+2·-3

Group like terms:

(x+2)=(2·-1)x+2·-3

Multiply the coefficients:

(x+2)=-2x+2·-3

Simplify the arithmetic:

(x+2)=-2x-6

Add to both sides:

(x+2)+2x=(-2x-6)+2x

Group like terms:

(x+2x)+2=(-2x-6)+2x

Simplify the arithmetic:

3x+2=(-2x-6)+2x

Group like terms:

3x+2=(-2x+2x)-6

Simplify the arithmetic:

3x+2=6

Subtract from both sides:

(3x+2)-2=-6-2

Simplify the arithmetic:

3x=62

Simplify the arithmetic:

3x=8

Divide both sides by :

(3x)3=-83

Simplify the fraction:

x=-83

3. List the solutions

x=-4,-83
(2 solution(s))

4. Graph

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