firstly, all d's i use will mean partial derivative 'do' because i don't have the font installed. sorry :(
please help me with these.. u got to use euler theorem
1. if z= xf(y/x) + g(y/x), show that x2(d2z/dx2) + 2xy(d2z/dxdy) + y2(d2z/dy2) =0
2. if z= (xy)/(x-y), PT (d2z/dx2) + 2(d2z/dxdy)...