$196n^2-144m^2$

$-\:\left(8+3\right)-\:\left[\left(6-3\right)\left(12+4\right)+5\right]$

$\int\left(8x-6\right)e^{-2x}dx$

$2x^2-5x+7$

$\lim_{x\to\infty}\left(\frac{x}{e^{2x}}\right)$

$\int\left(9x\cos\left(4x\right)\right)dx$

$\lim_{h\to0}\left(\frac{tan3\left(x-h\right)-tan3\left(x\right)}{h}\right)$