$\frac{cos^2\left(x\right)}{sen\left(x\right)-1}$

$b2-49$

$\left(2x^2-3xy+3y^2-8\right)-3\left(x^2+xy-4y^2-15\right)$

$ln\left(\frac{dy}{dx}\right)=e^{3x+2y}$

$\left(x+2a\right)\left(x^2-x\cdot2a+4a^2\right)$

$\frac{dx}{dy}=\frac{1+y^2}{ycosx}$

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