Question

求解等差数列已知等差数列{An}中``Am=p``An=q`m不等于n``求Am+n

Answer 1

An-Am=(n-m)d=q-p,则d=(q-p)/(n-m),故Am+n=An+（md)=q+m*(q-p)/(n-m)=(nq-mp)/(n-m)