等差数列an和bn中,a1+ b100= 100,b1+ a100=100,则数列〔an +bn 〕的前100项和为
问题描述:
等差数列an和bn中,a1+ b100= 100,b1+ a100=100,则数列〔an +bn 〕的前100项和为
答
S(100)=50(a1a100)+50(b1+b100)=50*(200)=10000
等差数列an和bn中,a1+ b100= 100,b1+ a100=100,则数列〔an +bn 〕的前100项和为
S(100)=50(a1a100)+50(b1+b100)=50*(200)=10000