Question

设Sn ,Tn分别为等差数列{an}{bn}的前n项和,Sn/Tn=(5n-2)/(n+3),则an/bn=?

Answer 1

an=[a1+a(2n-1)]/2bn=[b1+b(2n-1)]/2S(2n-1)={[a1+a(2n-1)]/2}*(2n-1)=an*(2n-1)T(2n-1)={[b1+b(2n-1)]/2}*(2n-1)=bn*(2n-1)S(2n-1)/T(2n-1)=an/bn所以an/bn=S(2n-1)/T(2n-1)=[5*(2n-1)-2]/[(2n-1)+3]=(10n-7)/(2n+2...