- #1
Cosmophile
- 111
- 2
Homework Statement
Find the regions of increase and decrease for ##f(x) = -3 \cot^{-1}(x)##
2. The attempt at a solution
My instructor and I disagree. The answer he gave was ##(-\infty, \infty)##, while my answer was ##(-\infty, 0) \cup (0, \infty)##.
My reasoning is this: ##-3\cot ^{-1}(x)## is not defined for ##x=0##. So, we cannot say what the behavior of the function is (increasing, decreasing, constant) at ##x=0##.
If my reasoning is wrong, I would like to understand why.