$\lim_{x\to3}\left(\frac{x-3}{\sqrt{x+13}-4}\right)$

$\int\frac{26m+26}{\left(m^2+1\right)\left(m-1\right)^3}dm$

$\lim_{x\to0}\left(-2\right)\frac{\left(x^2-4\right)}{\left(x^2+2\right)}$

$\frac{d^2y}{dx^2}\:y=\frac{x-1}{x+1}$

$12x^6b^5-6x^4b^{10}$

$\left(9x^2+7y^3\right)^2=81x^4+126x^2y^3+49y^6$

$\lim_{x\to1}\left(2x^3-3x+5\right)$