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Solution - Absolute value equations

Exact form: =78,-18
=\frac{7}{8} , -\frac{1}{8}
Decimal form: =0.875,0.125
=0.875 , -0.125

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
|+4|=|8x3|
without the absolute value bars:

|x|=|y||+4|=|8x3|
x=+y(+4)=(8x3)
x=y(+4)=(8x3)
+x=y(+4)=(8x3)
x=y(+4)=(8x3)

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||+4|=|8x3|
x=+y , +x=y(+4)=(8x3)
x=y , x=y(+4)=(8x3)

2. Solve the two equations for

5 additional steps

(4)=(8x-3)

Swap sides:

(8x-3)=(4)

Add to both sides:

(8x-3)+3=(4)+3

Simplify the arithmetic:

8x=(4)+3

Simplify the arithmetic:

8x=7

Divide both sides by :

(8x)8=78

Simplify the fraction:

x=78

8 additional steps

(4)=-(8x-3)

Expand the parentheses:

(4)=-8x+3

Swap sides:

-8x+3=(4)

Subtract from both sides:

(-8x+3)-3=(4)-3

Simplify the arithmetic:

-8x=(4)-3

Simplify the arithmetic:

8x=1

Divide both sides by :

(-8x)-8=1-8

Cancel out the negatives:

8x8=1-8

Simplify the fraction:

x=1-8

Move the negative sign from the denominator to the numerator:

x=-18

3. List the solutions

=78,-18
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|+4|
y=|8x3|
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.