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Solution - Absolute value equations

Exact form: =78,-38
=\frac{7}{8} , -\frac{3}{8}
Decimal form: =0.875,0.375
=0.875 , -0.375

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
|+5|=|8x2|
without the absolute value bars:

|x|=|y||+5|=|8x2|
x=+y(+5)=(8x2)
x=y(+5)=(8x2)
+x=y(+5)=(8x2)
x=y(+5)=(8x2)

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||+5|=|8x2|
x=+y , +x=y(+5)=(8x2)
x=y , x=y(+5)=(8x2)

2. Solve the two equations for

5 additional steps

(5)=(8x-2)

Swap sides:

(8x-2)=(5)

Add to both sides:

(8x-2)+2=(5)+2

Simplify the arithmetic:

8x=(5)+2

Simplify the arithmetic:

8x=7

Divide both sides by :

(8x)8=78

Simplify the fraction:

x=78

8 additional steps

(5)=-(8x-2)

Expand the parentheses:

(5)=-8x+2

Swap sides:

-8x+2=(5)

Subtract from both sides:

(-8x+2)-2=(5)-2

Simplify the arithmetic:

-8x=(5)-2

Simplify the arithmetic:

8x=3

Divide both sides by :

(-8x)-8=3-8

Cancel out the negatives:

8x8=3-8

Simplify the fraction:

x=3-8

Move the negative sign from the denominator to the numerator:

x=-38

3. List the solutions

=78,-38
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|+5|
y=|8x2|
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.