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Solution - Absolute value equations

Exact form: a=-12
a=-\frac{1}{2}
Decimal form: a=0.5
a=-0.5

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+3|
without the absolute value bars:

|x|=|y||a2|=|a+3|
x=+y(a2)=(a+3)
x=y(a2)=(a+3)
+x=y(a2)=(a+3)
x=y(a2)=(a+3)

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+3|
x=+y , +x=y(a2)=(a+3)
x=y , x=y(a2)=(a+3)

2. Solve the two equations for a

5 additional steps

(a-2)=(a+3)

Subtract from both sides:

(a-2)-a=(a+3)-a

Group like terms:

(a-a)-2=(a+3)-a

Simplify the arithmetic:

-2=(a+3)-a

Group like terms:

-2=(a-a)+3

Simplify the arithmetic:

2=3

The statement is false:

2=3

The equation is false so it has no solution.

10 additional steps

(a-2)=-(a+3)

Expand the parentheses:

(a-2)=-a-3

Add to both sides:

(a-2)+a=(-a-3)+a

Group like terms:

(a+a)-2=(-a-3)+a

Simplify the arithmetic:

2a-2=(-a-3)+a

Group like terms:

2a-2=(-a+a)-3

Simplify the arithmetic:

2a2=3

Add to both sides:

(2a-2)+2=-3+2

Simplify the arithmetic:

2a=3+2

Simplify the arithmetic:

2a=1

Divide both sides by :

(2a)2=-12

Simplify the fraction:

a=-12

3. Graph

Each line represents the function of one side of the equation:
y=|a2|
y=|a+3|
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.