$$\int\frac{1}{\left(x^2+a^2\right)^5}dx$$

$$\left(x^2-y^2\right)dx+3xydy$$

$$\lim_{x\to0}\left(\cos\left(3x\right)\right)^{\frac{2}{x}}$$

$$\lim_{x\to1}\left(\frac{\sqrt{x-1}}{x+1}\right)$$

$$\frac{dy}{dx}=\frac{3x^2}{e^y}$$

$$12.005\cdot2$$