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Solution - Absolute value equations

Exact form: x=-11,-19
x=-11 , -\frac{1}{9}
Decimal form: x=11,0.111
x=-11 , -0.111

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
|5x6|=|4x+5|
without the absolute value bars:

|x|=|y||5x6|=|4x+5|
x=+y(5x6)=(4x+5)
x=y(5x6)=(4x+5)
+x=y(5x6)=(4x+5)
x=y(5x6)=(4x+5)

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||5x6|=|4x+5|
x=+y , +x=y(5x6)=(4x+5)
x=y , x=y(5x6)=(4x+5)

2. Solve the two equations for x

10 additional steps

(-5x-6)=(-4x+5)

Add to both sides:

(-5x-6)+4x=(-4x+5)+4x

Group like terms:

(-5x+4x)-6=(-4x+5)+4x

Simplify the arithmetic:

-x-6=(-4x+5)+4x

Group like terms:

-x-6=(-4x+4x)+5

Simplify the arithmetic:

x6=5

Add to both sides:

(-x-6)+6=5+6

Simplify the arithmetic:

x=5+6

Simplify the arithmetic:

x=11

Multiply both sides by :

-x·-1=11·-1

Remove the one(s):

x=11·-1

Simplify the arithmetic:

x=11

12 additional steps

(-5x-6)=-(-4x+5)

Expand the parentheses:

(-5x-6)=4x-5

Subtract from both sides:

(-5x-6)-4x=(4x-5)-4x

Group like terms:

(-5x-4x)-6=(4x-5)-4x

Simplify the arithmetic:

-9x-6=(4x-5)-4x

Group like terms:

-9x-6=(4x-4x)-5

Simplify the arithmetic:

9x6=5

Add to both sides:

(-9x-6)+6=-5+6

Simplify the arithmetic:

9x=5+6

Simplify the arithmetic:

9x=1

Divide both sides by :

(-9x)-9=1-9

Cancel out the negatives:

9x9=1-9

Simplify the fraction:

x=1-9

Move the negative sign from the denominator to the numerator:

x=-19

3. List the solutions

x=-11,-19
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|5x6|
y=|4x+5|
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.