$$\frac{-2\cos\left(x\right)\left(1-\cos\left(x\right)\right)}{\sin\left(x\right)\left(1+\cos\left(x\right)\right)}$$

$$\frac{1}{\sqrt{x^2+13}}$$

$$\frac{2a^5+a^3+5a-8}{a+1}$$

$$\left(4w+2\right)\left(4w+5\right)$$

$$9a^2b+3ab-2a^2b+5ab+4$$

$$\lim_{n\to\infty}\left(\frac{6n^3+n^2-n}{3n^3+n+10n^2}\right)$$

$$\frac{3}{5}m^2-2mn+\frac{1}{10}m^2-\frac{1}{3}mn+2m-2m^2$$