$\int9x\left(x^2+7\right)^{-2}dx$

$\lim_{x\to\infty}\left(27-\frac{27\left(n+1\right)\left(2n+1\right)}{6n^2}\right)$

$\lim_{x\to0}\left(\frac{x\cdot tanx}{1-cos\left(2x\right)}\right)$

$\lim_{x\to0}\left(\frac{2^x-2}{x}\right)$

$11=9+x$

$\lim_{x\to\infty}\:\left(5+\frac{1}{x}\right)^{\frac{3}{x}}$

$\left(\sqrt{13}\right)^2$