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

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

$sqrt\left(\frac{sec\:t\:-\:cos\:t}{sec\:t}\right)$

$\left(7+x^{12}\right)\cdot\:\left(\frac{dy}{dx}\right)=\frac{x^{11}}{y}$

$\int2x^2\cos\left(9x\right)dx$

$\frac{\cot^2\left(x\right)cos^2\left(x\right)}{\cot^2\left(x\right)-\cos^2\left(x\right)}$

$\int\frac{3xe^{8x}}{2}dx$