$\left(y\right)dy\:=\:-\frac{\left(1+y^2\right)dx}{x}$

$\lim_{x\to\infty}\frac{e^{2x}}{2x}$

$\int\:\:\frac{lnt^2}{t}dt$

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

$\int_{-\pi}^{\pi}\frac{1}{\pi}xcosnxdx$

$\frac{\left(x^2+1\right)dy}{dx}=\left(x+1\right)\left(y^2-1\right)$

$\frac{dy}{dx}=\frac{2x+1}{y-3}$