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Solution - Absolute value equations

Exact form: x=113,-79
x=\frac{11}{3} , -\frac{7}{9}
Mixed number form: x=323,-79
x=3\frac{2}{3} , -\frac{7}{9}
Decimal form: x=3.667,0.778
x=3.667 , -0.778

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
|x+3|=2|x-13|
without the absolute value bars:

|x|=|y||x+3|=2|x-13|
x=+y(x+3)=2(x-13)
x=-y(x+3)=2(-(x-13))
+x=y(x+3)=2(x-13)
-x=y-(x+3)=2(x-13)

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+3|=2|x-13|
x=+y , +x=y(x+3)=2(x-13)
x=-y , -x=y(x+3)=2(-(x-13))

2. Solve the two equations for x

14 additional steps

(x+3)=2·(x+-13)

Expand the parentheses:

(x+3)=x·2+(-1·2)3

Simplify the arithmetic:

(x+3)=2x+-23

Subtract from both sides:

(x+3)-2x=(2x+-23)-2x

Group like terms:

(x-2x)+3=(2x+-23)-2x

Simplify the arithmetic:

-x+3=(2x+-23)-2x

Group like terms:

-x+3=(2x-2x)+-23

Simplify the arithmetic:

-x+3=-23

Subtract from both sides:

(-x+3)-3=(-23)-3

Simplify the arithmetic:

-x=(-23)-3

Convert the integer into a fraction:

-x=-23+-93

Combine the fractions:

-x=(-2-9)3

Combine the numerators:

-x=-113

Multiply both sides by :

-x·-1=(-113)·-1

Remove the one(s):

x=(-113)·-1

Remove the one(s):

x=113

18 additional steps

(x+3)=2·(-(x+-13))

Expand the parentheses:

(x+3)=2·(-x+13)

(x+3)=-x·2+(1·2)3

Group like terms:

(x+3)=(-1·2)x+(1·2)3

Multiply the coefficients:

(x+3)=-2x+(1·2)3

Simplify the arithmetic:

(x+3)=-2x+23

Add to both sides:

(x+3)+2x=(-2x+23)+2x

Group like terms:

(x+2x)+3=(-2x+23)+2x

Simplify the arithmetic:

3x+3=(-2x+23)+2x

Group like terms:

3x+3=(-2x+2x)+23

Simplify the arithmetic:

3x+3=23

Subtract from both sides:

(3x+3)-3=(23)-3

Simplify the arithmetic:

3x=(23)-3

Convert the integer into a fraction:

3x=23+-93

Combine the fractions:

3x=(2-9)3

Combine the numerators:

3x=-73

Divide both sides by :

(3x)3=(-73)3

Simplify the fraction:

x=(-73)3

Simplify the arithmetic:

x=-7(3·3)

x=-79

3. List the solutions

x=113,-79
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|x+3|
y=2|x-13|
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.