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Solution - Absolute value equations

Exact form:

x = 3, \frac{5}{11}

x=3 , \frac{5}{11}

Decimal form:

x = 3, 0.455

x=3 , 0.455

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
$| 8 x - 10 | = | 3 x + 5 |$
without the absolute value bars:

$\| x \| = \| y \|$	$\| 8 x - 10 \| = \| 3 x + 5 \|$
$x = + y$	$(8 x - 10) = (3 x + 5)$
$x = - y$	$(8 x - 10) = - (3 x + 5)$
$+ x = y$	$(8 x - 10) = (3 x + 5)$
$- x = y$	$- (8 x - 10) = (3 x + 5)$

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:

$\| x \| = \| y \|$	$\| 8 x - 10 \| = \| 3 x + 5 \|$
$x = + y$ , $+ x = y$	$(8 x - 10) = (3 x + 5)$
$x = - y$ , $- x = y$	$(8 x - 10) = - (3 x + 5)$

2. Solve the two equations for x

11 additional steps

$(8 x - 10) = (3 x + 5)$

Subtract from both sides:

$(8 x - 10) - 3 x = (3 x + 5) - 3 x$

Group like terms:

$(8 x - 3 x) - 10 = (3 x + 5) - 3 x$

Simplify the arithmetic:

$5 x - 10 = (3 x + 5) - 3 x$

Group like terms:

$5 x - 10 = (3 x - 3 x) + 5$

Simplify the arithmetic:

$5 x - 10 = 5$

Add to both sides:

$(5 x - 10) + 10 = 5 + 10$

Simplify the arithmetic:

$5 x = 5 + 10$

Simplify the arithmetic:

$5 x = 15$

Divide both sides by :

$\frac{(5 x)}{5} = \frac{15}{5}$

Simplify the fraction:

$x = \frac{15}{5}$

Find the greatest common factor of the numerator and denominator:

$x = \frac{(3 \cdot 5)}{(1 \cdot 5)}$

Factor out and cancel the greatest common factor:

$x = 3$

10 additional steps

$(8 x - 10) = - (3 x + 5)$

Expand the parentheses:

$(8 x - 10) = - 3 x - 5$

Add to both sides:

$(8 x - 10) + 3 x = (- 3 x - 5) + 3 x$

Group like terms:

$(8 x + 3 x) - 10 = (- 3 x - 5) + 3 x$

Simplify the arithmetic:

$11 x - 10 = (- 3 x - 5) + 3 x$

Group like terms:

$11 x - 10 = (- 3 x + 3 x) - 5$

Simplify the arithmetic:

$11 x - 10 = - 5$

Add to both sides:

$(11 x - 10) + 10 = - 5 + 10$

Simplify the arithmetic:

$11 x = - 5 + 10$

Simplify the arithmetic:

$11 x = 5$

Divide both sides by :

$\frac{(11 x)}{11} = \frac{5}{11}$

Simplify the fraction:

$x = \frac{5}{11}$

3. List the solutions

$x = 3, \frac{5}{11}$
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
$y = | 8 x - 10 |$
$y = | 3 x + 5 |$
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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