$4mn\:+\:5mn$

$-\int\:6x^2\sqrt[6]{4-\frac{1}{2}x^3}dx$

$\lim_{x\to0}\left(\frac{e^{2x}-2x-\cos\left(x\right)}{x-sin\left(x\right)}\right)$

$\left(2mn-3m^2\:\right)^2$

$\lim_{x\to0}\left(2.6xf+1.3f-7\right)$

$\left(tsn\left(x\right)\cdot sin\left(x\right)\right)=secx-cosx$

$\frac{\left(x^2-40x-65\right)}{x^2-25}\:-\:\frac{\left(4x+4\right)}{x+5}$