Enter an equation or problem

Camera input is not recognized!

Solution - Absolute value equations

Exact form:

r = 3, \frac{1}{2}

r=3 , \frac{1}{2}

Decimal form:

r = 3, 0.5

r=3 , 0.5

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
$| r + 2 | = | 3 r - 4 |$
without the absolute value bars:

$\| x \| = \| y \|$	$\| r + 2 \| = \| 3 r - 4 \|$
$x = + y$	$(r + 2) = (3 r - 4)$
$x = - y$	$(r + 2) = - (3 r - 4)$
$+ x = y$	$(r + 2) = (3 r - 4)$
$- x = y$	$- (r + 2) = (3 r - 4)$

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:

$\| x \| = \| y \|$	$\| r + 2 \| = \| 3 r - 4 \|$
$x = + y$ , $+ x = y$	$(r + 2) = (3 r - 4)$
$x = - y$ , $- x = y$	$(r + 2) = - (3 r - 4)$

2. Solve the two equations for r

13 additional steps

$(r + 2) = (3 r - 4)$

Subtract from both sides:

$(r + 2) - 3 r = (3 r - 4) - 3 r$

Group like terms:

$(r - 3 r) + 2 = (3 r - 4) - 3 r$

Simplify the arithmetic:

$- 2 r + 2 = (3 r - 4) - 3 r$

Group like terms:

$- 2 r + 2 = (3 r - 3 r) - 4$

Simplify the arithmetic:

$- 2 r + 2 = - 4$

Subtract from both sides:

$(- 2 r + 2) - 2 = - 4 - 2$

Simplify the arithmetic:

$- 2 r = - 4 - 2$

Simplify the arithmetic:

$- 2 r = - 6$

Divide both sides by :

$\frac{(- 2 r)}{- 2} = \frac{- 6}{- 2}$

Cancel out the negatives:

$\frac{2 r}{2} = \frac{- 6}{- 2}$

Simplify the fraction:

$r = \frac{- 6}{- 2}$

Cancel out the negatives:

$r = \frac{6}{2}$

Find the greatest common factor of the numerator and denominator:

$r = \frac{(3 \cdot 2)}{(1 \cdot 2)}$

Factor out and cancel the greatest common factor:

$r = 3$

12 additional steps

$(r + 2) = - (3 r - 4)$

Expand the parentheses:

$(r + 2) = - 3 r + 4$

Add to both sides:

$(r + 2) + 3 r = (- 3 r + 4) + 3 r$

Group like terms:

$(r + 3 r) + 2 = (- 3 r + 4) + 3 r$

Simplify the arithmetic:

$4 r + 2 = (- 3 r + 4) + 3 r$

Group like terms:

$4 r + 2 = (- 3 r + 3 r) + 4$

Simplify the arithmetic:

$4 r + 2 = 4$

Subtract from both sides:

$(4 r + 2) - 2 = 4 - 2$

Simplify the arithmetic:

$4 r = 4 - 2$

Simplify the arithmetic:

$4 r = 2$

Divide both sides by :

$\frac{(4 r)}{4} = \frac{2}{4}$

Simplify the fraction:

$r = \frac{2}{4}$

Find the greatest common factor of the numerator and denominator:

$r = \frac{(1 \cdot 2)}{(2 \cdot 2)}$

Factor out and cancel the greatest common factor:

$r = \frac{1}{2}$

3. List the solutions

$r = 3, \frac{1}{2}$
(2 solution(s))

4. Graph

Each line represents the function of one side of the equation:
$y = | r + 2 |$
$y = | 3 r - 4 |$
The equation is true where the two lines cross.

How did we do?

Please leave us feedback.

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 r

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 r

3. List the solutions

4. Graph

Why learn this

Terms and topics

Related links

Latest Related Drills Solved