设等差数列{an},{bn}的前n项和分别是Sn,Tn,且Sn/Tn=7n+2/n+3求a5/b5

设等差数列{an},{bn}的前n项和分别是Sn,Tn,且Sn/Tn=7n+2/n+3求a5/b5
设等差数列{an},{bn}的前n项和分别是Sn,Tn,且Sn/Tn=7n+2/n+3求a5/b5

设等差数列{an},{bn}的前n项和分别是Sn,Tn,且Sn/Tn=7n+2/n+3求a5/b5
因为S9=9×a5
T9=9×b5
所以a5/b5=S9/T9
因为Sn/Tn=7n+2/n+3
所以S9/T9=65/12

S9=9*a5
T9=9*b5
Sn/Tn=7n+2/n+3,n=9时，比值为65/12，所以a5/b5=65/12