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Solution - Absolute value equations

Exact form:

v = - \frac{6}{7}, 6

v=-\frac{6}{7} , 6

Decimal form:

v = - 0.857, 6

v=-0.857 , 6

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
$| - 3 v - 6 | = | 4 v |$
without the absolute value bars:

$\| x \| = \| y \|$	$\| - 3 v - 6 \| = \| 4 v \|$
$x = + y$	$(- 3 v - 6) = (4 v)$
$x = - y$	$(- 3 v - 6) = - (4 v)$
$+ x = y$	$(- 3 v - 6) = (4 v)$
$- x = y$	$- (- 3 v - 6) = (4 v)$

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:

$\| x \| = \| y \|$	$\| - 3 v - 6 \| = \| 4 v \|$
$x = + y$ , $+ x = y$	$(- 3 v - 6) = (4 v)$
$x = - y$ , $- x = y$	$(- 3 v - 6) = - (4 v)$

2. Solve the two equations for v

10 additional steps

$(- 3 v - 6) = 4 v$

Subtract from both sides:

$(- 3 v - 6) - 4 v = (4 v) - 4 v$

Group like terms:

$(- 3 v - 4 v) - 6 = (4 v) - 4 v$

Simplify the arithmetic:

$- 7 v - 6 = (4 v) - 4 v$

Simplify the arithmetic:

$- 7 v - 6 = 0$

Add to both sides:

$(- 7 v - 6) + 6 = 0 + 6$

Simplify the arithmetic:

$- 7 v = 0 + 6$

Simplify the arithmetic:

$- 7 v = 6$

Divide both sides by :

$\frac{(- 7 v)}{- 7} = \frac{6}{- 7}$

Cancel out the negatives:

$\frac{7 v}{7} = \frac{6}{- 7}$

Simplify the fraction:

$v = \frac{6}{- 7}$

Move the negative sign from the denominator to the numerator:

$v = \frac{- 6}{7}$

5 additional steps

$(- 3 v - 6) = - 4 v$

Add to both sides:

$(- 3 v - 6) + 6 = (- 4 v) + 6$

Simplify the arithmetic:

$- 3 v = (- 4 v) + 6$

Add to both sides:

$(- 3 v) + 4 v = ((- 4 v) + 6) + 4 v$

Simplify the arithmetic:

$v = ((- 4 v) + 6) + 4 v$

Group like terms:

$v = (- 4 v + 4 v) + 6$

Simplify the arithmetic:

$v = 6$

3. List the solutions

$v = - \frac{6}{7}, 6$
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
$y = | - 3 v - 6 |$
$y = | 4 v |$
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 v

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 v

3. List the solutions

4. Graph

Why learn this

Terms and topics

Related links

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