Section 14.5: Problem 3 (1 point) Find the derivative of f at point P in the direction of ii. f($!y):8$2+5y23 P: (178): =8i+3j 0911'ch : iii 6 aw) =tan'1(?y) +55in_1(%), P: (12,2), :1: 5+2j (Dfhi : Section 14.5: Problem 4 Previous Problem Problem List Next Problem (1 point) Find the derivative of f at point P in the direction of u. f(x, y, z) = 6x2 + 8y2 - 22, P = (7, -2,9), u - -6i + 3j + 6k (Duf) p = f(x, y, z) = cos(9xy) + e yz + In(4xz), P = (5, 0, 8), u = 7i - 7j + 6k (Duf) p =