2021高职高考数学复习第五章数列：考题直通课件

,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,高职高考,数学,含复习教材、,同步练习，另,有冲刺模拟,卷,考题直通,一、选择题,6,.,(2019,年,),若等差数列,a,n,的前,n,项和,S,n,=n,2,+a,(,a,R),则,a=,(,),A.,-,1,B.2,C.1,D.0,【,答案,】,D,a,1,=,S,1,=1+,a,;,n,2,时,a,n,=,S,n,-,S,n,-1,=(,n,2,+,a,)-(,n,-1),2,+,a,=2,n,-1,由题知,应有,a,1,满足,a,n,=2,n,-1,即,1+,a,=21-1,a,=0.,8.(2015,年,),若等比数列,a,n,满足,a,1,=4,a,2,=20,则,a,n,的前,n,项和,S,n,=,.,二、填空题,9.(2014,年,),已知等比数列,a,n,满足,a,n,0(,n,N*),且,a,5,a,7,=9,则,a,6,=,.,11.(2016,年,),在等差数列,a,n,中,已知,a,4,+,a,8,+,a,10,=50,则,a,2,+2,a,10,=,.,12.(2017,年,),设等比数列,a,n,的前,n,项和,则,a,n,的公比,q,=,.,14,.,(2019,年,),已知等差数列,a,n,的前,n,项和为,S,n,且,S,5,=,35,S,8,=,104,.,(1),求数列,a,n,的通项公式,;,(2),若数列,b,n,为等比数列,b,1,=a,2,且,b,2,=a,3,+,2,求数列,b,n,的公比,q,及前,n,项和,T,n,.,