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Solution - Absolute value equations

Exact form:

x = \frac{11}{7}, - \frac{1}{9}

x=\frac{11}{7} , -\frac{1}{9}

Mixed number form:

x = 1 \frac{4}{7}, - \frac{1}{9}

x=1\frac{4}{7} , -\frac{1}{9}

Decimal form:

x = 1.571, - 0.111

x=1.571 , -0.111

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
$| 8 x - 5 | = | x + 6 |$
without the absolute value bars:

$\| x \| = \| y \|$	$\| 8 x - 5 \| = \| x + 6 \|$
$x = + y$	$(8 x - 5) = (x + 6)$
$x = - y$	$(8 x - 5) = - (x + 6)$
$+ x = y$	$(8 x - 5) = (x + 6)$
$- x = y$	$- (8 x - 5) = (x + 6)$

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:

$\| x \| = \| y \|$	$\| 8 x - 5 \| = \| x + 6 \|$
$x = + y$ , $+ x = y$	$(8 x - 5) = (x + 6)$
$x = - y$ , $- x = y$	$(8 x - 5) = - (x + 6)$

2. Solve the two equations for x

9 additional steps

$(8 x - 5) = (x + 6)$

Subtract from both sides:

$(8 x - 5) - x = (x + 6) - x$

Group like terms:

$(8 x - x) - 5 = (x + 6) - x$

Simplify the arithmetic:

$7 x - 5 = (x + 6) - x$

Group like terms:

$7 x - 5 = (x - x) + 6$

Simplify the arithmetic:

$7 x - 5 = 6$

Add to both sides:

$(7 x - 5) + 5 = 6 + 5$

Simplify the arithmetic:

$7 x = 6 + 5$

Simplify the arithmetic:

$7 x = 11$

Divide both sides by :

$\frac{(7 x)}{7} = \frac{11}{7}$

Simplify the fraction:

$x = \frac{11}{7}$

10 additional steps

$(8 x - 5) = - (x + 6)$

Expand the parentheses:

$(8 x - 5) = - x - 6$

Add to both sides:

$(8 x - 5) + x = (- x - 6) + x$

Group like terms:

$(8 x + x) - 5 = (- x - 6) + x$

Simplify the arithmetic:

$9 x - 5 = (- x - 6) + x$

Group like terms:

$9 x - 5 = (- x + x) - 6$

Simplify the arithmetic:

$9 x - 5 = - 6$

Add to both sides:

$(9 x - 5) + 5 = - 6 + 5$

Simplify the arithmetic:

$9 x = - 6 + 5$

Simplify the arithmetic:

$9 x = - 1$

Divide both sides by :

$\frac{(9 x)}{9} = \frac{- 1}{9}$

Simplify the fraction:

$x = \frac{- 1}{9}$

3. List the solutions

$x = \frac{11}{7}, - \frac{1}{9}$
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
$y = | 8 x - 5 |$
$y = | x + 6 |$
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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