(b) Given differential equation dxdy=tan−1y−x1+y2⇒dydx=1+y2tan−1y−x⇒dydx+1+y2x=1+y2tan−1y is a linear differential equation, so. IF =e∫1+y2dy=etan−1y So, the solution is xetan−1y=∫etan−11+y2tan−1ydy+c⇒xetan−1y=∫t⋅etdt+c,{ where t=tan−1y}⇒xetan−1y=tet−∫et+c⇒xetan−1y=(tan−1y)etan−1y−etan−1y+c⇒xetan−1y=etan−1y((tan−1y)−1)+c