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Solution - Absolute value equations

Exact form: x=3,6
x=3 , 6

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
|2x+6|=2|x3|
without the absolute value bars:

|x|=|y||2x+6|=2|x3|
x=+y(2x+6)=2(x3)
x=y(2x+6)=2((x3))
+x=y(2x+6)=2(x3)
x=y(2x+6)=2(x3)

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||2x+6|=2|x3|
x=+y , +x=y(2x+6)=2(x3)
x=y , x=y(2x+6)=2((x3))

2. Solve the two equations for x

15 additional steps

(-2x+6)=2·(x-3)

Expand the parentheses:

(-2x+6)=2x+2·-3

Simplify the arithmetic:

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

Subtract from both sides:

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

Group like terms:

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

Simplify the arithmetic:

-4x+6=(2x-6)-2x

Group like terms:

-4x+6=(2x-2x)-6

Simplify the arithmetic:

4x+6=6

Subtract from both sides:

(-4x+6)-6=-6-6

Simplify the arithmetic:

4x=66

Simplify the arithmetic:

4x=12

Divide both sides by :

(-4x)-4=-12-4

Cancel out the negatives:

4x4=-12-4

Simplify the fraction:

x=-12-4

Cancel out the negatives:

x=124

Find the greatest common factor of the numerator and denominator:

x=(3·4)(1·4)

Factor out and cancel the greatest common factor:

x=3

9 additional steps

(-2x+6)=2·(-(x-3))

Expand the parentheses:

(-2x+6)=2·(-x+3)

(-2x+6)=2·-x+2·3

Group like terms:

(-2x+6)=(2·-1)x+2·3

Multiply the coefficients:

(-2x+6)=-2x+2·3

Simplify the arithmetic:

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

Add to both sides:

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

Group like terms:

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

Simplify the arithmetic:

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

Group like terms:

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

Simplify the arithmetic:

6=6

3. List the solutions

x=3,6
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|2x+6|
y=2|x3|
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.