# Math Help - limit of trig function

1. ## limit of trig function

How do I do this problem? I can't wrap my head around it...

(lim x --> infinity) tan^-1(x-x^3)

2. $x-x^3=-x(x^2-1)$

3. Originally Posted by colerelm1
How do I do this problem? I can't wrap my head around it...

(lim x --> infinity) tan^-1(x-x^3)
Is...

$\displaystyle \lim_{x \rightarrow \infty} (x-x^{3}) = -\infty$ (1)

...so that...

$\displaystyle \lim_{x \rightarrow \infty} \tan^{-1} (x-x^{3}) = -\frac{\pi}{2}$ (2)

Kind regards

$\chi$ $\sigma$