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Solution - Absolute value equations

Exact form: x=92,-214
x=\frac{9}{2} , -\frac{21}{4}
Mixed number form: x=412,-514
x=4\frac{1}{2} , -5\frac{1}{4}
Decimal form: x=4.5,5.25
x=4.5 , -5.25

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+2|=|13x+5|
without the absolute value bars:

|x|=|y||x+2|=|13x+5|
x=+y(x+2)=(13x+5)
x=-y(x+2)=-(13x+5)
+x=y(x+2)=(13x+5)
-x=y-(x+2)=(13x+5)

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+2|=|13x+5|
x=+y , +x=y(x+2)=(13x+5)
x=-y , -x=y(x+2)=-(13x+5)

2. Solve the two equations for x

19 additional steps

(x+2)=(13x+5)

Subtract from both sides:

(x+2)-13·x=(13x+5)-13x

Group like terms:

(x+-13·x)+2=(13·x+5)-13x

Group the coefficients:

(1+-13)x+2=(13·x+5)-13x

Convert the integer into a fraction:

(33+-13)x+2=(13·x+5)-13x

Combine the fractions:

(3-1)3·x+2=(13·x+5)-13x

Combine the numerators:

23·x+2=(13·x+5)-13x

Group like terms:

23·x+2=(13·x+-13x)+5

Combine the fractions:

23·x+2=(1-1)3x+5

Combine the numerators:

23·x+2=03x+5

Reduce the zero numerator:

23x+2=0x+5

Simplify the arithmetic:

23x+2=5

Subtract from both sides:

(23x+2)-2=5-2

Simplify the arithmetic:

23x=5-2

Simplify the arithmetic:

23x=3

Multiply both sides by inverse fraction :

(23x)·32=3·32

Group like terms:

(23·32)x=3·32

Multiply the coefficients:

(2·3)(3·2)x=3·32

Simplify the fraction:

x=3·32

Multiply the fraction(s):

x=(3·3)2

Simplify the arithmetic:

x=92

20 additional steps

(x+2)=-(13x+5)

Expand the parentheses:

(x+2)=-13x-5

Add to both sides:

(x+2)+13·x=(-13x-5)+13x

Group like terms:

(x+13·x)+2=(-13·x-5)+13x

Group the coefficients:

(1+13)x+2=(-13·x-5)+13x

Convert the integer into a fraction:

(33+13)x+2=(-13·x-5)+13x

Combine the fractions:

(3+1)3·x+2=(-13·x-5)+13x

Combine the numerators:

43·x+2=(-13·x-5)+13x

Group like terms:

43·x+2=(-13·x+13x)-5

Combine the fractions:

43·x+2=(-1+1)3x-5

Combine the numerators:

43·x+2=03x-5

Reduce the zero numerator:

43x+2=0x-5

Simplify the arithmetic:

43x+2=-5

Subtract from both sides:

(43x+2)-2=-5-2

Simplify the arithmetic:

43x=-5-2

Simplify the arithmetic:

43x=-7

Multiply both sides by inverse fraction :

(43x)·34=-7·34

Group like terms:

(43·34)x=-7·34

Multiply the coefficients:

(4·3)(3·4)x=-7·34

Simplify the fraction:

x=-7·34

Multiply the fraction(s):

x=(-7·3)4

Simplify the arithmetic:

x=-214

3. List the solutions

x=92,-214
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|x+2|
y=|13x+5|
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.