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Solution - Absolute value equations

Exact form: x=16,112
x=\frac{1}{6} , \frac{1}{12}
Decimal form: x=0.167,0.083
x=0.167 , 0.083

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

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

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

2. Solve the two equations for x

13 additional steps

(3x+-13)=x

Subtract from both sides:

(3x+-13)-x=x-x

Group like terms:

(3x-x)+-13=x-x

Simplify the arithmetic:

2x+-13=x-x

Simplify the arithmetic:

2x+-13=0

Add to both sides:

(2x+-13)+13=0+13

Combine the fractions:

2x+(-1+1)3=0+13

Combine the numerators:

2x+03=0+13

Reduce the zero numerator:

2x+0=0+13

Simplify the arithmetic:

2x=0+13

Simplify the arithmetic:

2x=13

Divide both sides by :

(2x)2=(13)2

Simplify the fraction:

x=(13)2

Simplify the arithmetic:

x=1(3·2)

x=16

13 additional steps

(3x+-13)=-x

Add to both sides:

(3x+-13)+x=-x+x

Group like terms:

(3x+x)+-13=-x+x

Simplify the arithmetic:

4x+-13=-x+x

Simplify the arithmetic:

4x+-13=0

Add to both sides:

(4x+-13)+13=0+13

Combine the fractions:

4x+(-1+1)3=0+13

Combine the numerators:

4x+03=0+13

Reduce the zero numerator:

4x+0=0+13

Simplify the arithmetic:

4x=0+13

Simplify the arithmetic:

4x=13

Divide both sides by :

(4x)4=(13)4

Simplify the fraction:

x=(13)4

Simplify the arithmetic:

x=1(3·4)

x=112

3. List the solutions

x=16,112
(2 solution(s))

4. Graph

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