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Solution - Absolute value equations

Exact form: x=7,1
x=7 , 1

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
|4x10|=|2x+4|
without the absolute value bars:

|x|=|y||4x10|=|2x+4|
x=+y(4x10)=(2x+4)
x=y(4x10)=(2x+4)
+x=y(4x10)=(2x+4)
x=y(4x10)=(2x+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||4x10|=|2x+4|
x=+y , +x=y(4x10)=(2x+4)
x=y , x=y(4x10)=(2x+4)

2. Solve the two equations for x

11 additional steps

(4x-10)=(2x+4)

Subtract from both sides:

(4x-10)-2x=(2x+4)-2x

Group like terms:

(4x-2x)-10=(2x+4)-2x

Simplify the arithmetic:

2x-10=(2x+4)-2x

Group like terms:

2x-10=(2x-2x)+4

Simplify the arithmetic:

2x10=4

Add to both sides:

(2x-10)+10=4+10

Simplify the arithmetic:

2x=4+10

Simplify the arithmetic:

2x=14

Divide both sides by :

(2x)2=142

Simplify the fraction:

x=142

Find the greatest common factor of the numerator and denominator:

x=(7·2)(1·2)

Factor out and cancel the greatest common factor:

x=7

11 additional steps

(4x-10)=-(2x+4)

Expand the parentheses:

(4x-10)=-2x-4

Add to both sides:

(4x-10)+2x=(-2x-4)+2x

Group like terms:

(4x+2x)-10=(-2x-4)+2x

Simplify the arithmetic:

6x-10=(-2x-4)+2x

Group like terms:

6x-10=(-2x+2x)-4

Simplify the arithmetic:

6x10=4

Add to both sides:

(6x-10)+10=-4+10

Simplify the arithmetic:

6x=4+10

Simplify the arithmetic:

6x=6

Divide both sides by :

(6x)6=66

Simplify the fraction:

x=66

Simplify the fraction:

x=1

3. List the solutions

x=7,1
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|4x10|
y=|2x+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.