$\left(n+7\right)\left(n-9\right)$

$9x^2-36x+4$

$\frac{1-cos\left(x\right)}{sen\left(x\right)}=\frac{sem\left(x\right)}{1+cos\left(x\right)}$

$-8x\:25x\:-40x\:-12$

$\frac{\left(1+\cos\left(x\right)\right)}{\sin\left(x\right)}+\frac{\left(\sin\left(x\right)\right)}{\left(1+\cos\left(x\right)\right)}$

$\int\frac{3x+4}{x\left(x+4\right)}dx$

$x^3+x^2-6x$