i am completely lost. there is an integral in my textbook in fermi dirac statistics whose result is written directly and am not able to understand . it is ∫⌽(u) du /exp.((u-uf)/kt) + 1 from 0 to ∞ expanded by tayor's series to give ∫⌽(u) du (from 0 to uf) +∏²/6 (kT)² [⌽'(u)] |at u=uf + 7∏⁴/360 (kT)⁴ [⌽''(u)] |at u=uf +................ where uf is such that function of u is zero for u greater than uf. plz reply as soon as possible. thanks.