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Solution - Absolute value equations

Exact form:

x = \frac{1}{6}, - \frac{1}{2}

x=\frac{1}{6} , -\frac{1}{2}

Decimal form:

x = 0.167, - 0.5

x=0.167 , -0.5

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
$| 8 x | = | - 4 x + 2 |$
without the absolute value bars:

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

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:

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

2. Solve the two equations for x

7 additional steps

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

Add to both sides:

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

Simplify the arithmetic:

$12 x = (- 4 x + 2) + 4 x$

Group like terms:

$12 x = (- 4 x + 4 x) + 2$

Simplify the arithmetic:

$12 x = 2$

Divide both sides by :

$\frac{(12 x)}{12} = \frac{2}{12}$

Simplify the fraction:

$x = \frac{2}{12}$

Find the greatest common factor of the numerator and denominator:

$x = \frac{(1 \cdot 2)}{(6 \cdot 2)}$

Factor out and cancel the greatest common factor:

$x = \frac{1}{6}$

8 additional steps

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

Expand the parentheses:

$8 x = 4 x - 2$

Subtract from both sides:

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

Simplify the arithmetic:

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

Group like terms:

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

Simplify the arithmetic:

$4 x = - 2$

Divide both sides by :

$\frac{(4 x)}{4} = \frac{- 2}{4}$

Simplify the fraction:

$x = \frac{- 2}{4}$

Find the greatest common factor of the numerator and denominator:

$x = \frac{(- 1 \cdot 2)}{(2 \cdot 2)}$

Factor out and cancel the greatest common factor:

$x = \frac{- 1}{2}$

3. List the solutions

$x = \frac{1}{6}, - \frac{1}{2}$
(2 solution(s))

4. Graph

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

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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

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