$\lim_{x\to-4}\left(\frac{x^4-2x^3-19x^2+32x+48}{x^2-16}\right)$

$\left(ab^7+c\right)\left(c-ab^7\right)$

$\lim_{x\to\infty}\left(\sqrt{x+8}-\sqrt{x+7}\right)$

$\frac{dx}{dy}=3x^2$

$\:\int\frac{1}{\left(x-1\right)\sqrt{\left(x-1\right)^2-4}}dx$

$4x^5-6x^2+3;\:x=-1$

$\frac{2f^2}{-2f^2}$