Fermi-sphere derivation

[cragar]

1. The problem statement, all variables and given/known data
use E_m=1/n (E)p(E)dE integral from 0 to Infinity
to derive E_m=3/5(E_f)


2. Relevant equations
n= p(E)dE integral from 0 to infinty
also n=Q*sqrt(E)dE integarl from 0 to (E_f)
p(E)=Q*sqrt(E)/(e^(E-E_f)+1)


3. The attempt at a solution
i tried doing integration by parts on it and moving stuff around but i cant seem to get it , is there a trick in using that the integral from o to infinty of p(E)dE = 0

[nickjer]

Please learn to use the latex command here. Otherwise most people won't understand what you are saying and won't help you. I can't even understand half of what you typed out.

[cragar]

http://en.wikipedia.org/wiki/Fermi_energy
scroll about half way down the page and you will see
total energy of a Fermi sphere , how do i show that , that integral turns into
3/5(Energy)