等差数列,{an},{bn}的前n项和分别是Sn,Tn.若Sn/Tn=2n/3n+1,求a5/b5的值
问题描述:
等差数列,{an},{bn}的前n项和分别是Sn,Tn.若Sn/Tn=2n/3n+1,求a5/b5的值
答
a5/b5=2a5/2b5=9(a1+a9)/9(b1+b9)=s9/t9=9/14
等差数列,{an},{bn}的前n项和分别是Sn,Tn.若Sn/Tn=2n/3n+1,求a5/b5的值
a5/b5=2a5/2b5=9(a1+a9)/9(b1+b9)=s9/t9=9/14