#1. d/dx[x^2+y^2=xy+3]#
#2x+2y dy/dx=xdy/dx +y#
#2y dy/dx -xdy/dx = y-2x#
#dy/dx (2y-x)=y-2x#
#dy/dx=(y-2x)/(2y-x)#
#2. siny/x+1/y = 1#
#d/dx[x^-1siny+y^-1 = 1]#
#1/xcosy dy/dx -siny/x^2 -1/y^2dy/dx=0#
#1/xcosy dy/dx -1/y^2dy/dx = sin y/x^2#
#dy/dx [cosy/x-1/y^2]=sin y/x^2#
#dy/dx =(sin y/x^2)/([cosy/x-1/y^2]) #