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Solution - Absolute value equations

Exact form: a=10,10
a=10 , 10

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
|a+10|=|a10|
without the absolute value bars:

|x|=|y||a+10|=|a10|
x=+y(a+10)=(a10)
x=y(a+10)=(a10)
+x=y(a+10)=(a10)
x=y(a+10)=(a10)

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||a+10|=|a10|
x=+y , +x=y(a+10)=(a10)
x=y , x=y(a+10)=(a10)

2. Solve the two equations for a

13 additional steps

(-a+10)=(a-10)

Subtract from both sides:

(-a+10)-a=(a-10)-a

Group like terms:

(-a-a)+10=(a-10)-a

Simplify the arithmetic:

-2a+10=(a-10)-a

Group like terms:

-2a+10=(a-a)-10

Simplify the arithmetic:

2a+10=10

Subtract from both sides:

(-2a+10)-10=-10-10

Simplify the arithmetic:

2a=1010

Simplify the arithmetic:

2a=20

Divide both sides by :

(-2a)-2=-20-2

Cancel out the negatives:

2a2=-20-2

Simplify the fraction:

a=-20-2

Cancel out the negatives:

a=202

Find the greatest common factor of the numerator and denominator:

a=(10·2)(1·2)

Factor out and cancel the greatest common factor:

a=10

5 additional steps

(-a+10)=-(a-10)

Expand the parentheses:

(-a+10)=-a+10

Add to both sides:

(-a+10)+a=(-a+10)+a

Group like terms:

(-a+a)+10=(-a+10)+a

Simplify the arithmetic:

10=(-a+10)+a

Group like terms:

10=(-a+a)+10

Simplify the arithmetic:

10=10

3. List the solutions

a=10,10
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|a+10|
y=|a10|
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.