$$\int_{\frac{\pi}{5}}^{\frac{3 \pi}{10}}\left[\frac{\tan x}{\tan x+\cot x}\right] d x=$$

$$\int_\limits0^1\left(\frac{x^2-2}{x^2+1}\right) d x=$$

$$\int_\limits{-5}^5 \log \left(\frac{7-x}{7+x}\right) d x=$$

$$\int_0^a \sqrt{\frac{x}{a-x}} d x=$$