191. $\int \frac{d x}{(\arcsin x)^{5} \sqrt{1-x^{2}}}$.
Solution. $\int \frac{d x}{(\arcsin x)^{5} \sqrt{1-x^{2}}}=\left|\begin{array}{l}\arcsin x=t \\ \frac{d x}{\sqrt{1-x^{2}}}=d t\end{array}\right|=\int \frac{d t}{t^{5}}=\int t^{-5} d t=$ $=-\frac{1}{4} t^{-4}+C=-\frac{1}{4(\arcsin x)^{4}}+C$.