116. $\int \frac{2 d x}{3 \sqrt{1-x^{2}}}$.

Translate the text above into English, keeping the original text's line breaks and format, and output the translation result directly.

116. $\int \frac{2 d x}{3 \sqrt{1-x^{2}}}$.

116. $\int \frac{2 d x}{3 \sqrt{1-x^{2}}}$.

(Note: The mathematical expression is already in English and does not require translation.)
Solution. Applying property 2 and formula $\mathrm{X}$, we find

$$
\int \frac{2 d x}{3 \sqrt{1-x^{2}}}=\frac{2}{3} \int \frac{d x}{\sqrt{1-x^{2}}}=\frac{2}{3} \arcsin x+C
$$

By differentiating the result, we obtain the integrand. Therefore, the solution is correct.