$\frac{sin\left(t\right)}{cos\left(t\right)-cos^3\left(t\right)}$

$\lim_{x\to4}\left(\frac{\sqrt{x-2}-\sqrt{2}}{x-4}\right)$

$\frac{\cos\left(5x\right)-\cos\left(15x\right)}{\sin\left(15x\right)-\sin\left(5x\right)}$

$y=x+5ln\left|x+1\right|+c$

$14m^2+21$

$\left(6x-4y^3\right)^2$

$\frac{x}{10}+\frac{1}{5}=\frac{x}{5}$