include mathematical justincat 1. Answer True or false for each of the following and then give justification for your answer. An answer of True or false without justification will receive No credit. (a) If f(x,y) is a function and i = (1, 1), then Daf (x,y) = VS (1, 1) . i is the directional derivative of the function f (x, y) in the direction of the vector i. (b) If lim f (r. v) = L exists , then / (5,x]) - bier+1?(b) If lim f(x,y) = L exists, then / (2,]) = Lass- 17 (c) If |IVF (x, v/) || = 5 for some function f (5, y), the maximum value of the direc- tional derivative is Daf (r, 7/) - 5 in the direction is the unit vector w/