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Solution - Absolute value equations

Exact form: x=-3,37
x=-3 , \frac{3}{7}
Decimal form: x=3,0.429
x=-3 , 0.429

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|=12|3x-3|
without the absolute value bars:

|x|=|y||2x|=12|3x-3|
x=+y(2x)=12(3x-3)
x=-y(2x)=12(-(3x-3))
+x=y(2x)=12(3x-3)
-x=y-(2x)=12(3x-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||2x|=12|3x-3|
x=+y , +x=y(2x)=12(3x-3)
x=-y , -x=y(2x)=12(-(3x-3))

2. Solve the two equations for x

17 additional steps

2x=12·(3x-3)

Multiply the fraction(s):

2x=(1·(3x-3))2

Break up the fraction:

2x=3x2+-32

Subtract from both sides:

(2x)-3x2=(3x2+-32)-3x2

Group the coefficients:

(2+-32)x=(3x2+-32)-3x2

Convert the integer into a fraction:

(42+-32)x=(3x2+-32)-3x2

Combine the fractions:

(4-3)2x=(3x2+-32)-3x2

Combine the numerators:

12x=(3x2+-32)-3x2

Group like terms:

12·x=(3x2+-32x)+-32

Combine the fractions:

12·x=(3-3)2x+-32

Combine the numerators:

12·x=02x+-32

Reduce the zero numerator:

12x=0x+-32

Simplify the arithmetic:

12x=-32

Multiply both sides by inverse fraction :

(12x)·21=(-32)·21

Group like terms:

(12·2)x=(-32)·21

Multiply the coefficients:

(1·2)2x=(-32)·21

Simplify the fraction:

x=(-32)·21

Multiply the fraction(s):

x=(-3·2)2

Simplify the arithmetic:

x=3

18 additional steps

2x=12·(-(3x-3))

Multiply the fraction(s):

2x=(1·(-(3x-3)))2

Expand the parentheses:

2x=(-3x+3)2

Break up the fraction:

2x=-3x2+32

Add to both sides:

(2x)+32·x=(-3x2+32)+32x

Group the coefficients:

(2+32)x=(-3x2+32)+32x

Convert the integer into a fraction:

(42+32)x=(-3x2+32)+32x

Combine the fractions:

(4+3)2·x=(-3x2+32)+32x

Combine the numerators:

72·x=(-3x2+32)+32x

Group like terms:

72·x=(-3x2+32x)+32

Combine the fractions:

72·x=(-3+3)2x+32

Combine the numerators:

72·x=02x+32

Reduce the zero numerator:

72x=0x+32

Simplify the arithmetic:

72x=32

Multiply both sides by inverse fraction :

(72x)·27=(32)·27

Group like terms:

(72·27)x=(32)·27

Multiply the coefficients:

(7·2)(2·7)x=(32)·27

Simplify the fraction:

x=(32)·27

Multiply the fraction(s):

x=(3·2)(2·7)

Simplify the arithmetic:

x=37

3. List the solutions

x=-3,37
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|2x|
y=12|3x-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.