need help with these!

9. Use Stokes's Theorem to evaluate F . dr . In this case, C is oriented counterclockwise as viewed from above. F(x, y, z) = 2yi + 3zj + xk C: triangle with vertices (3, 0, 0), (0, 3, 0), (0, 0, 3) 10. (a) Show that F (x , y ) = (3 x2 y2 , 2 x3 y - 4) is a conservative vector field and then (b) find a potential function. (c) Evaluate W = [ F(x, y) . dr where Cruns fre (1, 2) to (-1, 1) i. Find the volume of the parallelepiped with three adjacent edges formed by (2, 1, 0), (-1, 2, 0), and (1, 1, 2). ii. Using the definition of the limit of a function of two variables, show that lim (x,y)-(1,-3) y = -3