$4x<20$

$\left(97d^8\:+\:48e^9+22f^2\right)^2$

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

$\int\frac{3}{5}x^8dx$

$\left(3x\:.\:4x^2\right)^3$

$\frac{d^2y}{dx}\left(y\right)-2\frac{dy}{dx}\left(y\right)+y=0$

$\sec\left(\frac{\pi}{4}\right)dy=e^{2x}dx$