Question

设数列{an}{bn}均为等差数列,公差都不为0,无穷数列liman/bn=3,则无穷数列limb1+b2+...+bn

Answer 1

an=a1+(n-1)m

bn=b1+(n-1)p

则liman/bn=m/p=3

1im(b1+b2+...+bn)/n*a3n=lim(nb1+n(n-1)p/2)/n*(a1+(3n-1)m）=p/6m=1/18