$tan\left(x\right)\:+\:tan\left(y\right)\:=\:\frac{sin\left(x\:+\:y\right)}{cos\left(x\right)\:cos\left(y\right)}$

$343\cdot2401$

$\frac{dy}{dx}=5e^{x-y}$

$4x+2y=10$

$\left(21x^2-16y^3\right)\left(21x^2+16y^3\right)$

$\int\left(arctan\left(\frac{9}{x}\right)\right)dx$

$\frac{3\sqrt{x}}{2}-2\sqrt{x^3}$