等差数列〔an 〕的前n 项和为Sn,已知Sm等于a ,Sn 减Sn-m 等于b ,n ,m 是正的
等差数列〔an 〕的前n 项和为Sn,已知Sm等于a ,Sn 减Sn-m 等于b ,n ,m 是正的
{an}是等差数列前n项和Sn已知Sm=a Sn-Sn-m=b 求Sn
已知等差数列{an}的前n项和为Sn若Sn=Sm(n不等于m)则Sn+m=?
等差数列中前n项和为Sn若Sm等于n,Sn等于m求S{m+n}
已知等差数列{An}前n项的和Sn,若Sm/Sn=m²/n²,则a5/a6
若等差数列{An}的前m项和为Sm,前n项和为Sn,且Sm:Sn=m²:n²,则Am:An=?
已知等差数列an的前n项和为sn,且sm=sn(m不等于n)求s(m+n)
设等差数列{an}的前n项和为Sn,若存在正整数m,n(m<n),使得Sm=Sn,则Sm+n=0
等差数列an前n项和为Sn=m,Sm=n,求Sm+n的值
Sn为等差数列的前n项和,Sn=m,Sm=n,求:Sm+n
等差数列(an),前n项和为Sn.(1)Sm=n,Sn=m.求Sm+n的值(2)Sm=Sn(m不等于n)求Sm+n的值
1.等差数列{an},{bn}的前n项和分别为Sn,Tn,(1)若Sm=n,Sn=m,求Sn+m