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Solution - Absolute value equations

Exact form: x=-263,289
x=-\frac{26}{3} , \frac{28}{9}
Mixed number form: x=-823,319
x=-8\frac{2}{3} , 3\frac{1}{9}
Decimal form: x=8.667,3.111
x=-8.667 , 3.111

Other Ways to Solve

Absolute value equations

Step-by-step explanation

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

|-2x+13|+|x-9|=0

Add |x9| to both sides of the equation:

|-2x+13|+|x-9|-|x-9|=-|x-9|

Simplify the arithmetic

|-2x+13|=-|x-9|

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
|-2x+13|=-|x-9|
without the absolute value bars:

|x|=|y||-2x+13|=-|x-9|
x=+y(-2x+13)=-(x-9)
x=-y(-2x+13)=--(x-9)
+x=y(-2x+13)=-(x-9)
-x=y-(-2x+13)=-(x-9)

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||-2x+13|=-|x-9|
x=+y , +x=y(-2x+13)=-(x-9)
x=-y , -x=y(-2x+13)=--(x-9)

3. Solve the two equations for x

16 additional steps

(-2x+13)=-(x-9)

Expand the parentheses:

(-2x+13)=-x+9

Add to both sides:

(-2x+13)+x=(-x+9)+x

Group like terms:

(-2x+x)+13=(-x+9)+x

Simplify the arithmetic:

-x+13=(-x+9)+x

Group like terms:

-x+13=(-x+x)+9

Simplify the arithmetic:

-x+13=9

Subtract from both sides:

(-x+13)-13=9-13

Combine the fractions:

-x+(1-1)3=9-13

Combine the numerators:

-x+03=9-13

Reduce the zero numerator:

-x+0=9-13

Simplify the arithmetic:

-x=9-13

Convert the integer into a fraction:

-x=273+-13

Combine the fractions:

-x=(27-1)3

Combine the numerators:

-x=263

Multiply both sides by :

-x·-1=(263)·-1

Remove the one(s):

x=(263)·-1

Remove the one(s):

x=-263

18 additional steps

(-2x+13)=-(-(x-9))

NT_MSLUS_MAINSTEP_RESOLVE_DOUBLE_MINUS:

(-2x+13)=x-9

Subtract from both sides:

(-2x+13)-x=(x-9)-x

Group like terms:

(-2x-x)+13=(x-9)-x

Simplify the arithmetic:

-3x+13=(x-9)-x

Group like terms:

-3x+13=(x-x)-9

Simplify the arithmetic:

-3x+13=-9

Subtract from both sides:

(-3x+13)-13=-9-13

Combine the fractions:

-3x+(1-1)3=-9-13

Combine the numerators:

-3x+03=-9-13

Reduce the zero numerator:

-3x+0=-9-13

Simplify the arithmetic:

-3x=-9-13

Convert the integer into a fraction:

-3x=-273+-13

Combine the fractions:

-3x=(-27-1)3

Combine the numerators:

-3x=-283

Divide both sides by :

(-3x)-3=(-283)-3

Cancel out the negatives:

3x3=(-283)-3

Simplify the fraction:

x=(-283)-3

Simplify the arithmetic:

x=-28(3·-3)

x=289

4. List the solutions

x=-263,289
(2 solution(s))

5. Graph

Each line represents the function of one side of the equation:
y=|-2x+13|
y=-|x-9|
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.