don't know what to do algebra

Let  \(a,b,c,d,e,f\) be nonnegative real numbers.

(a) Prove that
\((a^2 + b^2)^2 (c^4 + d^4)(e^4 + f^4) \ge (ace + bdf)^4.\)
(b) Prove that
\((a^2 + b^2)(c^2 + d^2)(e^2 + f^2) \ge (ace + bdf)^2.\)

I have solved part (a), but I need help for (b) I used cauchy for (a) and I think you have to use it for (b)