(a) Find the minimum and maximum of f(x, y, z) = x2 +y2 +z subject to the constraint x2 +2y2 +4z2 = 1.
(b) Suppose the constraint was changed to x2 + 2y2 + 4z2 = 1.5. Without re-solving the problem under the new constraint, estimate the maximum value of f under the new constraint.