If g=𝜳(u,v)where u = x^2-y^2&v=2xy S.T ∂^2g/∂x^2 + ∂^2g/∂y^2 = 4(x^2 + y^2)[∂^2𝜳/∂u^2 + ∂^2𝜳/∂v^2], 22.02 MB, 16:02