$x'=\frac{-100t}{\left(x-10\right)}$

$\int\frac{1}{m^3+m^2}dm$

$\frac{d^2}{dx^2}\left(\frac{x^3+7}{x}\right)$

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

$\left(20+x\right)\frac{dy}{dx}=6y$

$\frac{x^3-4}{x^2+8}$

$\frac{1}{\sin\left(2x\right)}+\frac{1}{\tan\left(2x\right)}=\cot\left(x\right)$