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Solution - Absolute value equations

Exact form: x=3,0
x=3 , 0

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+3|=3|x1|
without the absolute value bars:

|x|=|y||x+3|=3|x1|
x=+y(x+3)=3(x1)
x=y(x+3)=3((x1))
+x=y(x+3)=3(x1)
x=y(x+3)=3(x1)

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+3|=3|x1|
x=+y , +x=y(x+3)=3(x1)
x=y , x=y(x+3)=3((x1))

2. Solve the two equations for x

15 additional steps

(x+3)=3·(x-1)

Expand the parentheses:

(x+3)=3x+3·-1

Simplify the arithmetic:

(x+3)=3x-3

Subtract from both sides:

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

Group like terms:

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

Simplify the arithmetic:

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

Group like terms:

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

Simplify the arithmetic:

2x+3=3

Subtract from both sides:

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

Simplify the arithmetic:

2x=33

Simplify the arithmetic:

2x=6

Divide both sides by :

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

Cancel out the negatives:

2x2=-6-2

Simplify the fraction:

x=-6-2

Cancel out the negatives:

x=62

Find the greatest common factor of the numerator and denominator:

x=(3·2)(1·2)

Factor out and cancel the greatest common factor:

x=3

13 additional steps

(x+3)=3·(-(x-1))

Expand the parentheses:

(x+3)=3·(-x+1)

(x+3)=3·-x+3·1

Group like terms:

(x+3)=(3·-1)x+3·1

Multiply the coefficients:

(x+3)=-3x+3·1

Simplify the arithmetic:

(x+3)=-3x+3

Add to both sides:

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

Group like terms:

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

Simplify the arithmetic:

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

Group like terms:

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

Simplify the arithmetic:

4x+3=3

Subtract from both sides:

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

Simplify the arithmetic:

4x=33

Simplify the arithmetic:

4x=0

Divide both sides by the coefficient:

x=0

3. List the solutions

x=3,0
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|x+3|
y=3|x1|
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.