Please help me solve this problem. and if you have a chance can you help me solve the 3rd part of the second problem please? it seems that I can't figure it out. Thank You!

Consider the following. (Round your answers to four decimal places.) f(x, y) = ye* (a) Find f(2, 1) and f(2.6, 1.95) and calculate Az. f(2, 1) = ((2.6, 1.95) = Az = (b) Use the total differential dz to approximate Az. dz =Find the four second partial derivatives. Observe that the second mixed partials are equal. Z = 4 - 4xy + By3 azz 12-2 ax-2 azz -4 axdy azz = ay X = -4 ayax