Compute the directional derivative of f (x, y,=) =xy- at the point (3,2, 1) in the direction of (5,4,1) 20 A 5 B (4, 12,36) C 104 D 42 E None of the aboveWhat is the slope of the tangent line to x -=y at the point (-1,1)? A B - 1 C - 21/ 3 3 D E None of the above