Question

Solve: |3r - 12| = 0

Answer 1

Absolute values give two answers.
First,
3r - 12 = +0
3r = 12
r = 4
Second,
3r - 12 = -0
r = 4
In this case r = 4 because positive and negative zero are identical. However, it is common for the positive and negative versions to be significant.

Answer 2

\[3r + 12 = \pm0\]
4,4