4) (5) Find the points on the surface y = 9 + xz that are closest to the origin. 5) (5) Use Lagrangian multipliers to find the minimum value of w = x2 + y2 + z subjected to the condition x + y + z =1. 6) (5) Using Lagrangian multipliers find the maximum and minimum values of f(x, y) = 8x2 -Zy subjected to the constraint x2 + y2 = 1.7) (5) Compute 1 + (x - 1)2 + 4y2dA, R = [0,3]x[0,2] R Both by using dxdy and by dydx. 8) (5) Use the Midpoint Rule to estimate the volume under f (x, y) = 4x + 8y and above the rectangle given by 0