$\left(2x+y\right)dx+\left(x+3\right)dy=0$

$\left(11x+13\right)\left(11x-6\right)$

$\int\frac{x^3}{\left(x^2+1\right)\left(x-1\right)\left(x+1\right)}\:dx$

$\frac{1+sen\left(x\right)+tg\left(x\right)}{1+cos\left(x\right)+ctg\left(x\right)}$

$\frac{1+\frac{x}{y}}{\frac{y}{x}}$

$\int\left(3x^{-2}\cdot\left(1-x^{-1}\right)^2\right)dx$

$\frac{x+3}{3}=9$