$\left(x-2\right)\left(5x^6-4x^4+6x^2+9\right)$

$\lim_{x\to0}\left(\frac{\cos\left(x-1\right)}{\ln\left(x+1\right)}\right)$

$\left(2z-2\right)$

$a^2-8a-16$

$\lim_{x\to\:13}\left(\frac{x^2-13}{x^2-169}\right)$

$3x\:+\:4x\:=\:28$

$\lim_{x\to0}\left(\frac{ln\left(3x^2+1\right)}{1-e^{-x^2}}\right)$