sin(x +y^2) +3xy=1
[cos(x+y^2)]*(dx+2ydy)+3ydx+3xdy=0
(cos(x+y^2)+3y)dx+(2ycos(x+y^2)+3x)dy=0
dy/dx=-(cos(x+y^2)+3y)/(2ycos(x+y^2)+3x)