$\frac{dy}{dx}=\tan\left(4\cdot x\right)$

$-8a^3b+6a^3b-2a^3b+a^3b$

$\lim_{x\to3}\left(\frac{\left|x^2-9\right|}{\left|x-3\right|}\right)$

$\left(5ax-2y\right)^2$

$\int\frac{x^2+2x-1}{x^2+9}dx$

$xy=x+y+218$

$\int\left(cos^4\left(6x\right)sin\left(6x\right)\right)dx$