$tanx\cdot\frac{1}{cotx}=tan^2x$

$2a\left(x-3\right)+6b\left(x-3\right)-5c\left(x-3\right)$

$5x\le12$

$\lim_{x\to\infty}\left(\frac{\log\left(x^2\right)}{x}\right)$

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

$cosx+cos\left(x+y\right)=0$

$\left(5z+3\right)\left(-5z-3\right)$