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Solution - Absolute value equations

Exact form: x=73,-12
x=\frac{7}{3} , -\frac{1}{2}
Mixed number form: x=213,-12
x=2\frac{1}{3} , -\frac{1}{2}
Decimal form: x=2.333,0.5
x=2.333 , -0.5

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
|9x4|=|3x+10|
without the absolute value bars:

|x|=|y||9x4|=|3x+10|
x=+y(9x4)=(3x+10)
x=y(9x4)=(3x+10)
+x=y(9x4)=(3x+10)
x=y(9x4)=(3x+10)

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||9x4|=|3x+10|
x=+y , +x=y(9x4)=(3x+10)
x=y , x=y(9x4)=(3x+10)

2. Solve the two equations for x

11 additional steps

(9x-4)=(3x+10)

Subtract from both sides:

(9x-4)-3x=(3x+10)-3x

Group like terms:

(9x-3x)-4=(3x+10)-3x

Simplify the arithmetic:

6x-4=(3x+10)-3x

Group like terms:

6x-4=(3x-3x)+10

Simplify the arithmetic:

6x4=10

Add to both sides:

(6x-4)+4=10+4

Simplify the arithmetic:

6x=10+4

Simplify the arithmetic:

6x=14

Divide both sides by :

(6x)6=146

Simplify the fraction:

x=146

Find the greatest common factor of the numerator and denominator:

x=(7·2)(3·2)

Factor out and cancel the greatest common factor:

x=73

12 additional steps

(9x-4)=-(3x+10)

Expand the parentheses:

(9x-4)=-3x-10

Add to both sides:

(9x-4)+3x=(-3x-10)+3x

Group like terms:

(9x+3x)-4=(-3x-10)+3x

Simplify the arithmetic:

12x-4=(-3x-10)+3x

Group like terms:

12x-4=(-3x+3x)-10

Simplify the arithmetic:

12x4=10

Add to both sides:

(12x-4)+4=-10+4

Simplify the arithmetic:

12x=10+4

Simplify the arithmetic:

12x=6

Divide both sides by :

(12x)12=-612

Simplify the fraction:

x=-612

Find the greatest common factor of the numerator and denominator:

x=(-1·6)(2·6)

Factor out and cancel the greatest common factor:

x=-12

3. List the solutions

x=73,-12
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|9x4|
y=|3x+10|
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.