等差数列{an},{bn}的前n项和分别为Sn与Tn,若Sn/Tn=2n/3n+1,则a10/b10= 求详解,
问题描述:
等差数列{an},{bn}的前n项和分别为Sn与Tn,若Sn/Tn=2n/3n+1,则a10/b10= 求详解,
答
等差
则a10/b10
=2a10/2b10
=(a1+a19)/(b1+b19)
=[(a1+a19)*19/2]/[(b1+b19)*19/2]
=S19/T19
=2*19/(3*19+1)
=19/29[(a1+a19)*19/2]/[(b1+b19)*19/2]这步怎么的出来的!上下*19/2采纳吧哦我知道了谢谢!