$0,1\frac{di}{dt}+50i=30$

$\int x^2\left(6x^2+4+\frac{1}{x^3}\right)dx$

$\frac{d}{dx}\left(\left(e^xcos\left(x\right)-e^xsin\left(x\right)\right)j\right)$

$x^2-4x-45$

$\frac{1}{z}+\frac{2}{z}+\frac{3}{z}+\frac{4}{z}=5$

$21x^4y^3-9x^2y^2+3xy$

$\left(\frac{9bf^2}{8b^3f^5}\right)^3$