$\lim_{x\to0}\left(\frac{tan\cdot x-x}{x^3}\right)$

$\left(9x-1\right)y'+9y=0$

$5-ab+3ab$

$\lim_{x\to\infty}\left(6\:+\:x^5\right)\frac{1}{\ln\left(5x^3+1\right)}$

$9\left(x+1\right)-3x\left(x+1\right)^2$

$\frac{d}{dx}y==2x^{\frac{1}{4}}+x^{\frac{6}{5}}$

$\frac{d}{dx}\left(4x^3\left(x^2+4\right)\left(x+4\right)^2tan^{-1}\left(2x\right)\right)$