Explanation:
An absolute value function in the form ...
f(x) = a|x -h| +k
will have its vertex at (x, y) = (h, k). The sign on scale factor "a" will tell you whether it opens upward (a > 0) or downward (a < 0).
If a is positive, the vertex is a minimum, and the range is [k, ∞).
If a is negative, the vertex is a maximum, and the range is (-∞, k].
