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Solution - Absolute value equations

Exact form: x=-53,-111
x=-\frac{5}{3} , -\frac{1}{11}
Mixed number form: x=-123,-111
x=-1\frac{2}{3} , -\frac{1}{11}
Decimal form: x=1.667,0.091
x=-1.667 , -0.091

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
|4x2|=|7x+3|
without the absolute value bars:

|x|=|y||4x2|=|7x+3|
x=+y(4x2)=(7x+3)
x=y(4x2)=(7x+3)
+x=y(4x2)=(7x+3)
x=y(4x2)=(7x+3)

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||4x2|=|7x+3|
x=+y , +x=y(4x2)=(7x+3)
x=y , x=y(4x2)=(7x+3)

2. Solve the two equations for x

11 additional steps

(4x-2)=(7x+3)

Subtract from both sides:

(4x-2)-7x=(7x+3)-7x

Group like terms:

(4x-7x)-2=(7x+3)-7x

Simplify the arithmetic:

-3x-2=(7x+3)-7x

Group like terms:

-3x-2=(7x-7x)+3

Simplify the arithmetic:

3x2=3

Add to both sides:

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

Simplify the arithmetic:

3x=3+2

Simplify the arithmetic:

3x=5

Divide both sides by :

(-3x)-3=5-3

Cancel out the negatives:

3x3=5-3

Simplify the fraction:

x=5-3

Move the negative sign from the denominator to the numerator:

x=-53

10 additional steps

(4x-2)=-(7x+3)

Expand the parentheses:

(4x-2)=-7x-3

Add to both sides:

(4x-2)+7x=(-7x-3)+7x

Group like terms:

(4x+7x)-2=(-7x-3)+7x

Simplify the arithmetic:

11x-2=(-7x-3)+7x

Group like terms:

11x-2=(-7x+7x)-3

Simplify the arithmetic:

11x2=3

Add to both sides:

(11x-2)+2=-3+2

Simplify the arithmetic:

11x=3+2

Simplify the arithmetic:

11x=1

Divide both sides by :

(11x)11=-111

Simplify the fraction:

x=-111

3. List the solutions

x=-53,-111
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
y=|4x2|
y=|7x+3|
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.