$6m^2+6m-9m^2$

$x^2-24x+9$

$\frac{tan\:xcot\:x}{1+tan^2x}+\frac{1}{csc^2}=1$

$\lim_{x\to1}\left(\frac{\sqrt{x+4}-\sqrt{5}}{x-1}\right)$

$\frac{-6}{\left(1\right)^7}$

$\frac{\csc\left(x\right)+1}{\cot\left(x\right)}-\frac{\cot\left(x\right)}{\csc\left(x\right)-1}=0$

$\left(3m-5n+6\right)+\left(-6m+8-20n\right)+\left(20n+12m-12\right)$