$\int\left(\frac{1}{4\left(1+3x\right)^2}\right)dx$

$-7m+3mn^2+12mn-7mn-3mn+6mn^2$

$\sqrt{2}sen\left(45-x\right)$

$\int\frac{1}{13\cos\left(x\right)-5}dx$

$\lim_{x\to0}\left(\frac{e^x-e^{-6}-2x}{x-sin\left(x\right)}\right)$

$\frac{\left(x^3-9x+20\right)}{x-5}$

$6\cdot8-10$