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Solution - Absolute value equations

Exact form: a=-38,-3
a=-\frac{3}{8} , -3
Decimal form: a=0.375,3
a=-0.375 , -3

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
|8a+3|=|8a3|
without the absolute value bars:

|x|=|y||8a+3|=|8a3|
x=+y(8a+3)=(8a3)
x=y(8a+3)=((8a3))
+x=y(8a+3)=(8a3)
x=y((8a+3))=(8a3)

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||8a+3|=|8a3|
x=+y , +x=y(8a+3)=(8a3)
x=y , x=y(8a+3)=((8a3))

2. Solve the two equations for a

15 additional steps

-(8a+3)=-(-8a-3)

Expand the parentheses:

-8a-3=-(-8a-3)

Expand the parentheses:

8a3=8a+3

Subtract from both sides:

(-8a-3)-8a=(8a+3)-8a

Group like terms:

(-8a-8a)-3=(8a+3)-8a

Simplify the arithmetic:

-16a-3=(8a+3)-8a

Group like terms:

-16a-3=(8a-8a)+3

Simplify the arithmetic:

16a3=3

Add to both sides:

(-16a-3)+3=3+3

Simplify the arithmetic:

16a=3+3

Simplify the arithmetic:

16a=6

Divide both sides by :

(-16a)-16=6-16

Cancel out the negatives:

16a16=6-16

Simplify the fraction:

a=6-16

Move the negative sign from the denominator to the numerator:

a=-616

Find the greatest common factor of the numerator and denominator:

a=(-3·2)(8·2)

Factor out and cancel the greatest common factor:

a=-38

6 additional steps

-(8a+3)=-(-(-8a-3))

Expand the parentheses:

-8a-3=-(-(-8a-3))

Resolve the double minus:

8a3=8a3

Add to both sides:

(-8a-3)+8a=(-8a-3)+8a

Group like terms:

(-8a+8a)-3=(-8a-3)+8a

Simplify the arithmetic:

-3=(-8a-3)+8a

Group like terms:

-3=(-8a+8a)-3

Simplify the arithmetic:

3=3

3. List the solutions

a=-38,-3
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|8a+3|
y=|8a3|
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.