a) Let be an reordering of . Prove that:

b) Assuming prove also:

Hello,

I have shown a) by using the inequality of arithmetic and geometric means.

But I have problems with b). I failed to use any inequalities of means.I tried to define

. Then I have

,

given the additional . Though it seemed smart, I couldn't make use of it.

Is there anybody able to help?

Thanks in advance,

mili