$36x^{2n}-9y^{4n+2}$

$\lim_{x\to-3}\left(\frac{x^2}{e^{-3x}}\right)$

$\frac{dy}{dx}=24+18x+28y+21xy$

$\frac{e^xdy}{dx}+xy^2=0$

$\lim_{x\to k}\left(\frac{sin\left(x\right)-sin\left(k\right)}{x-k}\right)$

$\frac{4x^5-3x^4-x^2-1}{x+2}$

$\left(\frac{7}{5}y\left(3\right)-\frac{2}{3}\right)\left(\frac{4}{7}y\left(3\right)-\frac{7}{3}\right)$