Just need to handle the 2nd part, finding the adjoint operator of D. Thx!

2. Consider the finite difference operator for two-dimensional data D : RnXN (Rnx(n-1), R(n-1)xn) defined by: For any X ERNXN, DX = (Y,Z) with Y ERnx(n-1) and Z ER(n-1) xn satisfying Yi, j = X 3+1 - Xij, i = 1,..., n, j = 1,...,n-1 and Zij = Xi+1,3 X,j i = 1,...,n-1, j = 1, ..., n. We equip the standard inner product on Rn and its induced norm. We also equip an inner product on (Rnx(n-1), R(n-1)xn) as ((Y,Z), (Y2, Z2)) := (Y1, Y2) + (21, 22) and its induced norm. (a) Show that ||D|