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Solution - Absolute value equations

Exact form: x=2
x=-2

Other Ways to Solve

Absolute value equations

Step-by-step explanation

1. Rewrite the equation with one absolute value terms on each side

|x|+|x+4|=0

Add |x+4| to both sides of the equation:

|x|+|x+4||x+4|=|x+4|

Simplify the arithmetic

|x|=|x+4|

2. 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
|x|=|x+4|
without the absolute value bars:

|x|=|y||x|=|x+4|
x=+y(x)=(x+4)
x=y(x)=(x+4)
+x=y(x)=(x+4)
x=y(x)=(x+4)

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||x|=|x+4|
x=+y , +x=y(x)=(x+4)
x=y , x=y(x)=(x+4)

3. Solve the two equations for x

8 additional steps

x=-(x+4)

Expand the parentheses:

x=x4

Add to both sides:

x+x=(-x-4)+x

Simplify the arithmetic:

2x=(-x-4)+x

Group like terms:

2x=(-x+x)-4

Simplify the arithmetic:

2x=4

Divide both sides by :

(2x)2=-42

Simplify the fraction:

x=-42

Find the greatest common factor of the numerator and denominator:

x=(-2·2)(1·2)

Factor out and cancel the greatest common factor:

x=2

5 additional steps

x=-(-(x+4))

NT_MSLUS_MAINSTEP_RESOLVE_DOUBLE_MINUS:

x=x+4

Subtract from both sides:

x-x=(x+4)-x

Simplify the arithmetic:

0=(x+4)-x

Group like terms:

0=(x-x)+4

Simplify the arithmetic:

0=4

The statement is false:

0=4

The equation is false so it has no solution.

4. List the solutions

x=2
(1 solution(s))

5. Graph

Each line represents the function of one side of the equation:
y=|x|
y=|x+4|
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.