$\frac{12x^9y^7}{3x^2y}$

$\lim_{x\to+\infty}\:\:x\left(\frac{1-3arctan\left(\frac{1}{x}\right).x^2}{x^2}\right)$

$e^{-y}-cx=1$

$\frac{d^5y}{dx^5}\left(x^6-3x^3+2x\right)$

$\int\left(\left(2x-9\right)^{-4}\right)dx$

$\lim_{x\to+\infty}\left(\frac{x}{\sqrt{x+x^2}}\right)$

$( x - 2 y ) ^ { 6 }$