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Solution - Absolute value equations

Exact form: a=2,2
a=2 , -2

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
|a2|=|a+2|
without the absolute value bars:

|x|=|y||a2|=|a+2|
x=+y(a2)=(a+2)
x=y(a2)=(a+2)
+x=y(a2)=(a+2)
x=y(a2)=(a+2)

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||a2|=|a+2|
x=+y , +x=y(a2)=(a+2)
x=y , x=y(a2)=(a+2)

2. Solve the two equations for a

11 additional steps

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

Add to both sides:

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

Group like terms:

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

Simplify the arithmetic:

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

Group like terms:

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

Simplify the arithmetic:

2a2=2

Add to both sides:

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

Simplify the arithmetic:

2a=2+2

Simplify the arithmetic:

2a=4

Divide both sides by :

(2a)2=42

Simplify the fraction:

a=42

Find the greatest common factor of the numerator and denominator:

a=(2·2)(1·2)

Factor out and cancel the greatest common factor:

a=2

5 additional steps

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

Expand the parentheses:

(a-2)=a-2

Subtract from both sides:

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

Group like terms:

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

Simplify the arithmetic:

-2=(a-2)-a

Group like terms:

-2=(a-a)-2

Simplify the arithmetic:

2=2

3. List the solutions

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

4. Graph

Each line represents the function of one side of the equation:
y=|a2|
y=|a+2|
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.