$\int\frac{\left(7x\right)}{\left(\sqrt[2]{3x^2-4}\right)}dx$

$\int_{-\pi}^{\pi}\left(\cos\left(9x\right)\right)dx$

$\left(7y^3x+2y\right)\cdot\left(7y^3x-2y\right)$

$\frac{9a\:-\:9b}{3a^3b-1}$

$\int\frac{x^2-2x-37}{x^2-3x-40}dx$

$\lim_{x\to0}\left(\frac{3\sin\left(x\right)-\sin\left(3x\right)}{x-\sin\left(x\right)}\right)$

$\left(1+tan^2u\right)\left(1-sen^2u\right)=1$