因此数列各项都是正,则公比q>0,a2=a1q
则：(a1＋a2)/2－√(a1a2)
=a1(1＋q)/2－a√(2)
=(1/2)a1(1－2√q＋q)
=(1/2)[√q－1]²>0
则：P>Q