$-\left(x+y\right)\left(x-y\right)$

$\lim_{x\to5}\left(\frac{x^2+25}{x-5}\right)$

$2\int_1^9\left(x^{-2}\right)dx$

$sec\left(x\right)\left(tan\left(x\right)\right)\left(cos\left(x\right)\right)$

$\int\frac{4x-8}{\left(2x+4\right)\left(3x+2\right)^2}dx$

$\lim_{x\to1}\frac{1}{1-x}-\frac{3}{1-x^3}$

$x^2+2x=-1$