$\int\frac{e^{x}}{\left(e^{x}-1\right)\left(e^{x}+4}dx$

$\:\left(2x+y\right)dx\:+\:\left(x-4y\right)dy\:=\:0$

$\lim_{x\to\infty}\left(\frac{3x^2+2x+1}{x^2}\right)$

$\lim_{x\to\infty}\left(\frac{x^{log\left(x\right)}}{a^n}\right)$

$7x-7\cdot x-9$

$6sinxcosx=2$

$2x^3y+4xy^7$