解设每项相差m
S20=S10+(S10+10*10m）
S100=10S10+90m*10+80m*10+70m*10+60m*10+50m*10+40m*10+30m*10+20m*10+10m*10
S110=S100+S10+100m*10
=-110
等差数列An中,Sn为前N项的和S100=10,S10=100,问S110——?
等差数列An中,Sn为前N项的和S100=10,S10=100,问S110——?
数学人气：979 ℃时间：2020-04-25 06:57:55
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