$18-\sqrt{-25}$

$\frac{3x+6}{3}$

$\int t^2in\left(t\right)\:dt$

$\frac{3x^2-x}{x-2}$

$\frac{d^2}{dx^2}\left(\frac{1}{\cot\left(x\right)-1}\right)$

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

$\lim_{x\to-1}\left(\frac{\sqrt[3]{3x-5}-2\sqrt{2+x}-5x-1}{x^2-1}\right)$