Enter an equation or problem

Camera input is not recognized!

Solution - Absolute value equations

Exact form:

x = - 4, - 8

x=-4 , -8

See steps

Step-by-step explanation

1. Rewrite the equation without absolute value bars

Use the rules:
$| x | = | y |$ → $x = \pm y$ and $| x | = | y |$ → $\pm x = y$
to write all four options of the equation
$- 2 | x + 4 | = | 2 x + 8 |$
without the absolute value bars:

$\| x \| = \| y \|$	$- 2 \| x + 4 \| = \| 2 x + 8 \|$
$x = + y$	$- 2 (x + 4) = (2 x + 8)$
$x = - y$	$- 2 (x + 4) = - (2 x + 8)$
$+ x = y$	$- 2 (x + 4) = (2 x + 8)$
$- x = y$	$- 2 (- (x + 4)) = (2 x + 8)$

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:

$\| x \| = \| y \|$	$- 2 \| x + 4 \| = \| 2 x + 8 \|$
$x = + y$ , $+ x = y$	$- 2 (x + 4) = (2 x + 8)$
$x = - y$ , $- x = y$	$- 2 (x + 4) = - (2 x + 8)$

2. Solve the two equations for x

15 additional steps

$- 2 \cdot (x + 4) = (2 x + 8)$

Expand the parentheses:

$- 2 x - 2 \cdot 4 = (2 x + 8)$

Simplify the arithmetic:

$- 2 x - 8 = (2 x + 8)$

Subtract from both sides:

$(- 2 x - 8) - 2 x = (2 x + 8) - 2 x$

Group like terms:

$(- 2 x - 2 x) - 8 = (2 x + 8) - 2 x$

Simplify the arithmetic:

$- 4 x - 8 = (2 x + 8) - 2 x$

Group like terms:

$- 4 x - 8 = (2 x - 2 x) + 8$

Simplify the arithmetic:

$- 4 x - 8 = 8$

Add to both sides:

$(- 4 x - 8) + 8 = 8 + 8$

Simplify the arithmetic:

$- 4 x = 8 + 8$

Simplify the arithmetic:

$- 4 x = 16$

Divide both sides by :

$\frac{(- 4 x)}{- 4} = \frac{16}{- 4}$

Cancel out the negatives:

$\frac{4 x}{4} = \frac{16}{- 4}$

Simplify the fraction:

$x = \frac{16}{- 4}$

Move the negative sign from the denominator to the numerator:

$x = \frac{- 16}{4}$

Find the greatest common factor of the numerator and denominator:

$x = \frac{(- 4 \cdot 4)}{(1 \cdot 4)}$

Factor out and cancel the greatest common factor:

$x = - 4$

7 additional steps

$- 2 \cdot (x + 4) = - (2 x + 8)$

Expand the parentheses:

$- 2 x - 2 \cdot 4 = - (2 x + 8)$

Simplify the arithmetic:

$- 2 x - 8 = - (2 x + 8)$

Expand the parentheses:

$- 2 x - 8 = - 2 x - 8$

Add to both sides:

$(- 2 x - 8) + 2 x = (- 2 x - 8) + 2 x$

Group like terms:

$(- 2 x + 2 x) - 8 = (- 2 x - 8) + 2 x$

Simplify the arithmetic:

$- 8 = (- 2 x - 8) + 2 x$

Group like terms:

$- 8 = (- 2 x + 2 x) - 8$

Simplify the arithmetic:

$- 8 = - 8$

3. List the solutions

$x = - 4, - 8$
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
$y = - 2 | x + 4 |$
$y = | 2 x + 8 |$
The equation is true where the two lines cross.

How did we do?

Please leave us feedback.

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.

Solution - Absolute value equations

Step-by-step explanation

1. Rewrite the equation without absolute value bars

2. Solve the two equations for x

3. List the solutions

4. Graph

Why learn this

Terms and topics

Related links

Solution - Absolute value equations

Step-by-step explanation

1. Rewrite the equation without absolute value bars

2. Solve the two equations for x

3. List the solutions

4. Graph

Why learn this

Terms and topics

Related links

Latest Related Drills Solved