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Solution - Absolute value equations

Exact form: w=-518
w=-\frac{5}{18}
Decimal form: w=0.278
w=-0.278

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
|w+79|=|w-29|
without the absolute value bars:

|x|=|y||w+79|=|w-29|
x=+y(w+79)=(w-29)
x=-y(w+79)=-(w-29)
+x=y(w+79)=(w-29)
-x=y-(w+79)=(w-29)

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||w+79|=|w-29|
x=+y , +x=y(w+79)=(w-29)
x=-y , -x=y(w+79)=-(w-29)

2. Solve the two equations for w

5 additional steps

(w+79)=(w+-29)

Subtract from both sides:

(w+79)-w=(w+-29)-w

Group like terms:

(w-w)+79=(w+-29)-w

Simplify the arithmetic:

79=(w+-29)-w

Group like terms:

79=(w-w)+-29

Simplify the arithmetic:

79=-29

The statement is false:

79=-29

The equation is false so it has no solution.

16 additional steps

(w+79)=-(w+-29)

Expand the parentheses:

(w+79)=-w+29

Add to both sides:

(w+79)+w=(-w+29)+w

Group like terms:

(w+w)+79=(-w+29)+w

Simplify the arithmetic:

2w+79=(-w+29)+w

Group like terms:

2w+79=(-w+w)+29

Simplify the arithmetic:

2w+79=29

Subtract from both sides:

(2w+79)-79=(29)-79

Combine the fractions:

2w+(7-7)9=(29)-79

Combine the numerators:

2w+09=(29)-79

Reduce the zero numerator:

2w+0=(29)-79

Simplify the arithmetic:

2w=(29)-79

Combine the fractions:

2w=(2-7)9

Combine the numerators:

2w=-59

Divide both sides by :

(2w)2=(-59)2

Simplify the fraction:

w=(-59)2

Simplify the arithmetic:

w=-5(9·2)

w=-518

3. Graph

Each line represents the function of one side of the equation:
y=|w+79|
y=|w-29|
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.