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Solution - Absolute value equations

Exact form:

v = \frac{11}{4}

v=\frac{11}{4}

Mixed number form:

v = 2 \frac{3}{4}

v=2\frac{3}{4}

Decimal form:

v = 2.75

v=2.75

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
$| 2 v - 2 | = | 2 v - 9 |$
without the absolute value bars:

$\| x \| = \| y \|$	$\| 2 v - 2 \| = \| 2 v - 9 \|$
$x = + y$	$(2 v - 2) = (2 v - 9)$
$x = - y$	$(2 v - 2) = - (2 v - 9)$
$+ x = y$	$(2 v - 2) = (2 v - 9)$
$- x = y$	$- (2 v - 2) = (2 v - 9)$

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:

$\| x \| = \| y \|$	$\| 2 v - 2 \| = \| 2 v - 9 \|$
$x = + y$ , $+ x = y$	$(2 v - 2) = (2 v - 9)$
$x = - y$ , $- x = y$	$(2 v - 2) = - (2 v - 9)$

2. Solve the two equations for v

5 additional steps

$(2 v - 2) = (2 v - 9)$

Subtract from both sides:

$(2 v - 2) - 2 v = (2 v - 9) - 2 v$

Group like terms:

$(2 v - 2 v) - 2 = (2 v - 9) - 2 v$

Simplify the arithmetic:

$- 2 = (2 v - 9) - 2 v$

Group like terms:

$- 2 = (2 v - 2 v) - 9$

Simplify the arithmetic:

$- 2 = - 9$

The statement is false:

$- 2 = - 9$

The equation is false so it has no solution.

10 additional steps

$(2 v - 2) = - (2 v - 9)$

Expand the parentheses:

$(2 v - 2) = - 2 v + 9$

Add to both sides:

$(2 v - 2) + 2 v = (- 2 v + 9) + 2 v$

Group like terms:

$(2 v + 2 v) - 2 = (- 2 v + 9) + 2 v$

Simplify the arithmetic:

$4 v - 2 = (- 2 v + 9) + 2 v$

Group like terms:

$4 v - 2 = (- 2 v + 2 v) + 9$

Simplify the arithmetic:

$4 v - 2 = 9$

Add to both sides:

$(4 v - 2) + 2 = 9 + 2$

Simplify the arithmetic:

$4 v = 9 + 2$

Simplify the arithmetic:

$4 v = 11$

Divide both sides by :

$\frac{(4 v)}{4} = \frac{11}{4}$

Simplify the fraction:

$v = \frac{11}{4}$

3. Graph

Each line represents the function of one side of the equation:
$y = | 2 v - 2 |$
$y = | 2 v - 9 |$
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. 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. Graph

Why learn this

Terms and topics

Related links

Latest Related Drills Solved