Let a, b, c, d, e, f be nonnegative real numbers.
(a) Prove that (a^2 + b^2)^2 (c^4 + d^4)(e^4 + f^4) >= 32abcdef.
(b) Prove that (a^2 + b^2)(c^2 + d^2)(e^2 + f^2) >= 8abcdef.
