Sn=(n+n^2)/2,如果用裂项法求和怎么求?RT~学了好久了,都忘记了.= =如果用裂项求1/S1+1/S2+……+1/Sn,怎么求.有什么通式么?
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![Sn=(n+n^2)/2,如果用裂项法求和怎么求?RT~学了好久了,都忘记了.= =如果用裂项求1/S1+1/S2+……+1/Sn,怎么求.有什么通式么?](/uploads/image/z/1389387-3-7.jpg?t=Sn%3D%28n%2Bn%5E2%29%2F2%2C%E5%A6%82%E6%9E%9C%E7%94%A8%E8%A3%82%E9%A1%B9%E6%B3%95%E6%B1%82%E5%92%8C%E6%80%8E%E4%B9%88%E6%B1%82%3FRT%7E%E5%AD%A6%E4%BA%86%E5%A5%BD%E4%B9%85%E4%BA%86%2C%E9%83%BD%E5%BF%98%E8%AE%B0%E4%BA%86.%3D+%3D%E5%A6%82%E6%9E%9C%E7%94%A8%E8%A3%82%E9%A1%B9%E6%B1%821%2FS1%2B1%2FS2%2B%E2%80%A6%E2%80%A6%2B1%2FSn%2C%E6%80%8E%E4%B9%88%E6%B1%82.%E6%9C%89%E4%BB%80%E4%B9%88%E9%80%9A%E5%BC%8F%E4%B9%88%3F)
Sn=(n+n^2)/2,如果用裂项法求和怎么求?RT~学了好久了,都忘记了.= =如果用裂项求1/S1+1/S2+……+1/Sn,怎么求.有什么通式么?
Sn=(n+n^2)/2,如果用裂项法求和怎么求?
RT~学了好久了,都忘记了.= =如果用裂项求1/S1+1/S2+……+1/Sn,怎么求.有什么通式么?
Sn=(n+n^2)/2,如果用裂项法求和怎么求?RT~学了好久了,都忘记了.= =如果用裂项求1/S1+1/S2+……+1/Sn,怎么求.有什么通式么?
1/Sn=2/(n+n^2)=2*(1/n(n+1))=2*(1/n -1/(n+1))
1/S1+1/S2+……+1/Sn=2*(1- 1/2 + 1/2 - 1/3 +……+1/n - 1/(n+1))=2*(1- 1/(n+1))=2-2/(n+1)
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