$\lim_{x\to3}\left(\frac{\left(e^{x^3}-e^{27}\right)}{x-3}\right)$

$\frac{tan^2t+1}{1+cos^2t}$

$ac+bd-ad-bc$

$\int5x^2e^{2x+1}dx$

$\frac{x^4+2}{x^2+4}$

$\lim\:_{x\to\:0}\frac{e^{x^2\left(x^2-2x+1\right)-1}}{arctan\left(x^2\left(4x^2+3x+1\right)\right)}$

$3-2x>-25-4x$