I need solve this assignment

Question 1 Not yet answered Marked out of 5.00 Flag question If z = -4xe3xy and x = Vt, y = -. Then, the value of Z at t = 8 is equal to Question 7 ( - 12 + 7 ) et Not yet answered Marked out of 5.00 Flag question Select one: O True O False Choose the normal vector of the tangent plane to the surface defined by Question 6 Not yet answered Z = e6x2+14xy-52 Marked out of 5.00 at the point (3, -4, -194 ) Flag question O Choose the direction vector for which the None of the others function f defined by O -20 f(x, y)= sin(5x) cos(3y) , 0> - 194 , has the maximum rate of change at the point ( 1, " ). O -20 82 e194 " e194 , 1 > None of the others O O