1. ## Finding asymptotes

f(x) = arctan(x^4 - x^2) Mr F says: As $x \rightarrow \pm \infty$, $f(x) \rightarrow \frac{\pi}{2}$.
f(x) = cot^-1 (x^2 - x^4) Mr F says: As $x \rightarrow \pm \infty$, $f(x) \rightarrow 0$. As $x \rightarrow 0$, $f(x) \rightarrow + \infty$.