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Solution - Absolute value equations

Exact form:

u = \frac{5}{13}, - \frac{5}{11}

u=\frac{5}{13} , -\frac{5}{11}

Decimal form:

u = 0.385, - 0.455

u=0.385 , -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
$| 12 u | = | - u + 5 |$
without the absolute value bars:

$\| x \| = \| y \|$	$\| 12 u \| = \| - u + 5 \|$
$x = + y$	$(12 u) = (- u + 5)$
$x = - y$	$(12 u) = - (- u + 5)$
$+ x = y$	$(12 u) = (- u + 5)$
$- x = y$	$- (12 u) = (- u + 5)$

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:

$\| x \| = \| y \|$	$\| 12 u \| = \| - u + 5 \|$
$x = + y$ , $+ x = y$	$(12 u) = (- u + 5)$
$x = - y$ , $- x = y$	$(12 u) = - (- u + 5)$

2. Solve the two equations for u

5 additional steps

$12 u = (- u + 5)$

Add to both sides:

$(12 u) + u = (- u + 5) + u$

Simplify the arithmetic:

$13 u = (- u + 5) + u$

Group like terms:

$13 u = (- u + u) + 5$

Simplify the arithmetic:

$13 u = 5$

Divide both sides by :

$\frac{(13 u)}{13} = \frac{5}{13}$

Simplify the fraction:

$u = \frac{5}{13}$

6 additional steps

$12 u = - (- u + 5)$

Expand the parentheses:

$12 u = u - 5$

Subtract from both sides:

$(12 u) - u = (u - 5) - u$

Simplify the arithmetic:

$11 u = (u - 5) - u$

Group like terms:

$11 u = (u - u) - 5$

Simplify the arithmetic:

$11 u = - 5$

Divide both sides by :

$\frac{(11 u)}{11} = \frac{- 5}{11}$

Simplify the fraction:

$u = \frac{- 5}{11}$

3. List the solutions

$u = \frac{5}{13}, - \frac{5}{11}$
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
$y = | 12 u |$
$y = | - u + 5 |$
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 u

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 u

3. List the solutions

4. Graph

Why learn this

Terms and topics

Related links

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