$\:-\:\left(9+5\cdot6-20\right)$

$\left(5-8+3\right)\left(10-15+7\right)\left(8+3\right)\:-3\left(25-21\right)\:+4\left(15-12\right)$

$12x^2-13-35$

$\int\:x^3\:\left(2-3x\right)^5dx$

$8,321+389,669$

$\lim_{x\to0}\left(\frac{\left(sin\left(2x\right)+x^2+2x\right)}{5x^2+tanx}\right)$

$\lim_{x\to0}\left(\frac{4x^2-5x}{1-3x^2}\right)$