高考数学复习第5章数列第3讲等比数列及其前n项和文市赛课公开课一等奖省名师优质课获奖课件.pptx

栏目导引,知能训练,轻松闯关,名师讲坛,素养提升,典例剖析,考点突破,教材回顾,夯实基础,第五章 数 列,第,3,讲等比数列及其前,n,项和,第五章 数 列,1/39,2,同一常数,公比,2/39,G,G,2,ab,3/39,a,1,q,n,1,na,1,4/39,a,p,a,q,5/39,6/39,7/39,8/39,D,9/39,B,10/39,C,11/39,4,在,9,与,243,中间插入两个数，使它们同这两个数成等比数列，则这两个数为,_,解析：设该数列公比为,q,，由题意知，,243,9,q,3,，得,q,3,27,，所以,q,3.,所以插入两个数分别为,9,3,27,，,27,3,81.,27,，,81,12/39,5,(,高考全国卷,),在数列,a,n,中，,a,1,2,，,a,n,1,2,a,n,，,S,n,为,a,n,前,n,项和若,S,n,126,，则,n,_,6,13/39,14/39,3,n,1,2,n,1,15/39,16/39,17/39,28,6,B,18/39,19/39,20/39,21/39,22/39,23/39,24/39,25/39,26/39,27/39,C,28/39,A,29/39,30/39,31/39,32/39,A,D,33/39,34/39,方法思想,分类讨论思想在求数列前,n,项和中应用,35/39,36/39,37/39,38/39,39/39,