Solve the differential equation (1+y^{2})tan^{-1} x dx + 2y(1+x^{2})dy = 0.
We have (1+y^{2})tan-1 xdx + 2y(1+x^{2})dy = 0⇒ (1+y^{2})tan-1 xdx + 2y(1+x^{2})dy