$-5\cdot\left(-4\right)+\left(-2\right)\cdot8$

$\frac{x^2-x^4+x^2-2}{x^2+1}$

$\cot^2a+1=\frac{1}{\sin^2}$

$2x^2-30x+180$

$\frac{dy}{dx}=24+18x+28y+21xy$

$\left(a^2+5a+4\right)\left(a+2\right)$

$\lim_{x\to0}\left(\frac{sin\left(2x\right)}{x}\right)^{\left(\frac{1}{x^2}\right)}$