$\lim_{x\to\infty}\left(\frac{7x_{+11}}{19x+17}\right)$

$\frac{1-cos\left(x\right)}{1+cos\left(c\right)}=\left(csc\left(x\right)-cot\left(x\right)\right)^2$

$\left(\frac{6mn^{-2}}{3m^{-1}n^2}\right)^{-3}$

$\frac{\cos\left(x\right)}{\cos\left(x\right)+\sin\left(x\right)}=\frac{1}{1+\tan\left(x\right)}$

$\frac{r^2d\phi\:}{dr}=k\:$

$( 2 a + 3 b ^ { 2 } ) ^ { 2 }$

$\left(x-40\right)\left(x+7\right)$