$75\cdot3$

$4-5x\ge19$

$\lim_{x\to3}\left(\frac{1-\sqrt{x+4}}{x+3}\right)$

$\left(n+3\right)\left(n+5\right)\left(mn+n^2\right)$

$\frac{d}{dx}\left(\frac{8}{3}\sqrt{x-1}x+2\sqrt{x-1}\right)$

$\frac{n^2}{9^n}x^n$

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