若两个等差数列｛an｝ ｛bn｝ 满足a1+a2+a3+.+an/b1+b2+b3+.+bn=7n+2/n+3 求a5/b5.

若两个等差数列｛an｝ ｛bn｝ 满足a1+a2+a3+.+an/b1+b2+b3+.+bn=7n+2/n+3 求a5/b5.
若两个等差数列｛an｝ ｛bn｝ 满足a1+a2+a3+.+an/b1+b2+b3+.+bn=7n+2/n+3 求a5/b5.

若两个等差数列｛an｝ ｛bn｝ 满足a1+a2+a3+.+an/b1+b2+b3+.+bn=7n+2/n+3 求a5/b5.
(a1+a2+a3+.+an)/(b1+b2+b3+.+bn)=7n+2/n+3
San/Tbn=(7n+2)/(n+3)
a5/b5=[1/2*(a1+a9)]/[1/2*(b1+b9)]
=9*[1/2*(a1+a9)]/9*[1/2*(b1+b9)]
=S9/T9
=(7*9+2)/(9+3)
=65/12