Partial Derivative – Calculating second order partial derivatives to x^m multiplied by y^n – Exercise 4317

z''_{xx} (x,y)=m(m-1)x^{m-2}y^n

z''_{yy} (x,y)=n(n-1)y^{n-2}x^m

z''_{xy} (x,y)=z''_{yx}(x,y)=mnx^{m-1}y^{n-1}