$\frac{a}{s}+\frac{b}{ts+1}$

$b+16\ge19$

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

$15,2\:+\:7$

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

$\frac{4x^3+4x^2-29x+18}{2x-3}$

$\lim_{x\to-1}\frac{x^2+8x+16}{x^2+x+3}$