$\lim\:_{t\to\:0}\frac{\left(e^t\right)}{2^t}$

$\cot^2\left(x\right)\cdot\sec^2\left(x\right)-\cot^2\left(x\right)=1$

$5ab;\:a=3,b=5$

$\lim_{x\to\infty}\left(1+\frac{12}{x}\right)^{\frac{x}{4}}$

$4x^2+18x-36$

$\int\frac{x^2+2}{\left(x+5\right)^2\left(x+2\right)}dx$

$\left(x-y+z-4\right)\left(x-y-z+4\right)$