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Solution - Absolute value equations

Exact form:

k = - \frac{2}{3}

k=-\frac{2}{3}

Decimal form:

k = - 0.667

k=-0.667

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

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

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:

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

2. Solve the two equations for k

7 additional steps

$(3 k - 2) = 3 \cdot (k + 2)$

Expand the parentheses:

$(3 k - 2) = 3 k + 3 \cdot 2$

Simplify the arithmetic:

$(3 k - 2) = 3 k + 6$

Subtract from both sides:

$(3 k - 2) - 3 k = (3 k + 6) - 3 k$

Group like terms:

$(3 k - 3 k) - 2 = (3 k + 6) - 3 k$

Simplify the arithmetic:

$- 2 = (3 k + 6) - 3 k$

Group like terms:

$- 2 = (3 k - 3 k) + 6$

Simplify the arithmetic:

$- 2 = 6$

The statement is false:

$- 2 = 6$

The equation is false so it has no solution.

16 additional steps

$(3 k - 2) = 3 \cdot (- (k + 2))$

Expand the parentheses:

$(3 k - 2) = 3 \cdot (- k - 2)$

$(3 k - 2) = 3 \cdot - k + 3 \cdot - 2$

Group like terms:

$(3 k - 2) = (3 \cdot - 1) k + 3 \cdot - 2$

Multiply the coefficients:

$(3 k - 2) = - 3 k + 3 \cdot - 2$

Simplify the arithmetic:

$(3 k - 2) = - 3 k - 6$

Add to both sides:

$(3 k - 2) + 3 k = (- 3 k - 6) + 3 k$

Group like terms:

$(3 k + 3 k) - 2 = (- 3 k - 6) + 3 k$

Simplify the arithmetic:

$6 k - 2 = (- 3 k - 6) + 3 k$

Group like terms:

$6 k - 2 = (- 3 k + 3 k) - 6$

Simplify the arithmetic:

$6 k - 2 = - 6$

Add to both sides:

$(6 k - 2) + 2 = - 6 + 2$

Simplify the arithmetic:

$6 k = - 6 + 2$

Simplify the arithmetic:

$6 k = - 4$

Divide both sides by :

$\frac{(6 k)}{6} = \frac{- 4}{6}$

Simplify the fraction:

$k = \frac{- 4}{6}$

Find the greatest common factor of the numerator and denominator:

$k = \frac{(- 2 \cdot 2)}{(3 \cdot 2)}$

Factor out and cancel the greatest common factor:

$k = \frac{- 2}{3}$

3. Graph

Each line represents the function of one side of the equation:
$y = | 3 k - 2 |$
$y = 3 | k + 2 |$
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 k

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 k

3. Graph

Why learn this

Terms and topics

Related links

Latest Related Drills Solved