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Solution - Absolute value equations

Exact form: z=17,17
z=17 , -17

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
|z+17|=|z+17|
without the absolute value bars:

|x|=|y||z+17|=|z+17|
x=+y(z+17)=(z+17)
x=y(z+17)=(z+17)
+x=y(z+17)=(z+17)
x=y(z+17)=(z+17)

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||z+17|=|z+17|
x=+y , +x=y(z+17)=(z+17)
x=y , x=y(z+17)=(z+17)

2. Solve the two equations for z

4 additional steps

(z+17)=(z+17)

Subtract from both sides:

(z+17)-z=(z+17)-z

Group like terms:

(z-z)+17=(z+17)-z

Simplify the arithmetic:

17=(z+17)-z

Group like terms:

17=(z-z)+17

Simplify the arithmetic:

17=17

12 additional steps

(z+17)=-(z+17)

Expand the parentheses:

(z+17)=-z-17

Add to both sides:

(z+17)+z=(-z-17)+z

Group like terms:

(z+z)+17=(-z-17)+z

Simplify the arithmetic:

2z+17=(-z-17)+z

Group like terms:

2z+17=(-z+z)-17

Simplify the arithmetic:

2z+17=17

Subtract from both sides:

(2z+17)-17=-17-17

Simplify the arithmetic:

2z=1717

Simplify the arithmetic:

2z=34

Divide both sides by :

(2z)2=-342

Simplify the fraction:

z=-342

Find the greatest common factor of the numerator and denominator:

z=(-17·2)(1·2)

Factor out and cancel the greatest common factor:

z=17

3. List the solutions

z=17,17
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|z+17|
y=|z+17|
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.