$\frac{dy}{dx}+3xy^3=0\:\:$

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

$\left(2^2\right)^3+\left(3^3\right)^1$

$\left(6y^2-3y^5\right)^2$

$\lim_{x\to0}\left(1+7x\right)^{\frac{3}{x}}$

$\lim_{x\to0}\left(\frac{a\cdot sen\left(x\right)-x\cdot e^x}{x^2}\right)$

$\left(1+\tan\left(y\right)\right)\left(1-\cot\left(y\right)\right)$