$3\cdot12$

$e\:=\:\left(x+5\right)\left(x-5\right)\:-\:\left(x+4\right)\left(x-4\right)$

$\int\left(1-csc\:t\:\:cot\:t\:\right)dt$

$\int\left(x^2+3x-1\right)\ln\left(x\right)dx$

$\frac{\frac{\left(x^2-xy+y^2\right)}{x^3+y^3}}{\frac{1}{x+y}}$

$8-n^2+6n$

$\int\frac{5x}{\sqrt{x^2-1}}dx$