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Solution - Absolute value equations

Exact form: x=2,1
x=2 , -1

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+5|=|3x3|
without the absolute value bars:

|x|=|y||x+5|=|3x3|
x=+y(x+5)=(3x3)
x=y(x+5)=(3x3)
+x=y(x+5)=(3x3)
x=y(x+5)=(3x3)

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+5|=|3x3|
x=+y , +x=y(x+5)=(3x3)
x=y , x=y(x+5)=(3x3)

2. Solve the two equations for x

13 additional steps

(-x+5)=(3x-3)

Subtract from both sides:

(-x+5)-3x=(3x-3)-3x

Group like terms:

(-x-3x)+5=(3x-3)-3x

Simplify the arithmetic:

-4x+5=(3x-3)-3x

Group like terms:

-4x+5=(3x-3x)-3

Simplify the arithmetic:

4x+5=3

Subtract from both sides:

(-4x+5)-5=-3-5

Simplify the arithmetic:

4x=35

Simplify the arithmetic:

4x=8

Divide both sides by :

(-4x)-4=-8-4

Cancel out the negatives:

4x4=-8-4

Simplify the fraction:

x=-8-4

Cancel out the negatives:

x=84

Find the greatest common factor of the numerator and denominator:

x=(2·4)(1·4)

Factor out and cancel the greatest common factor:

x=2

11 additional steps

(-x+5)=-(3x-3)

Expand the parentheses:

(-x+5)=-3x+3

Add to both sides:

(-x+5)+3x=(-3x+3)+3x

Group like terms:

(-x+3x)+5=(-3x+3)+3x

Simplify the arithmetic:

2x+5=(-3x+3)+3x

Group like terms:

2x+5=(-3x+3x)+3

Simplify the arithmetic:

2x+5=3

Subtract from both sides:

(2x+5)-5=3-5

Simplify the arithmetic:

2x=35

Simplify the arithmetic:

2x=2

Divide both sides by :

(2x)2=-22

Simplify the fraction:

x=-22

Simplify the fraction:

x=1

3. List the solutions

x=2,1
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|x+5|
y=|3x3|
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.