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Solution - Absolute value equations

Exact form:

k = 2, \frac{2}{5}

k=2 , \frac{2}{5}

Decimal form:

k = 2, 0.4

k=2 , 0.4

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

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

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:

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

2. Solve the two equations for k

6 additional steps

$(3 k - 2) = 2 k$

Subtract from both sides:

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

Group like terms:

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

Simplify the arithmetic:

$k - 2 = (2 k) - 2 k$

Simplify the arithmetic:

$k - 2 = 0$

Add to both sides:

$(k - 2) + 2 = 0 + 2$

Simplify the arithmetic:

$k = 0 + 2$

Simplify the arithmetic:

$k = 2$

10 additional steps

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

Group like terms:

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

Multiply the coefficients:

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

Add to both sides:

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

Group like terms:

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

Simplify the arithmetic:

$5 k - 2 = (- 2 k) + 2 k$

Simplify the arithmetic:

$5 k - 2 = 0$

Add to both sides:

$(5 k - 2) + 2 = 0 + 2$

Simplify the arithmetic:

$5 k = 0 + 2$

Simplify the arithmetic:

$5 k = 2$

Divide both sides by :

$\frac{(5 k)}{5} = \frac{2}{5}$

Simplify the fraction:

$k = \frac{2}{5}$

3. List the solutions

$k = 2, \frac{2}{5}$
(2 solution(s))

4. Graph

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

3. List the solutions

4. Graph

Why learn this

Terms and topics

Related links

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