(5分)已知等差数列$\{a_{n}\}$的公差不为零,$S_{n}$为其前$n$项和,若$S_{5}=0$,则$S_{i}(i=0$,1,2,$\ldots$,$100)$中不同的数值有 98 个. 分析:由等差数前$n$项和公式求出$a_{1}=-2d$,从而$S_{n}=\dfrac{d}{2}(n^{2}-5n)$,由此能求出结果. 解:$\because$等差数列$\{a_{n}\}$的公差不为零,$S_{n}$为其前$n$项和,$S_{5}=0$, $\therefore$${S}_{5}=5{a}_{1}+\dfrac{5\times 4}{2}d=0$,解得$a_{1}=-2d$, $\therefore S_{n}=na_{1}+\dfrac{n(n-1)}{2}d=-2nd+\dfrac{n(n-1)}{2}d=\dfrac{d}{2}(n^{2}-5n)$, $\because d\ne 0$,$\therefore S_{i}(i=0$,1,$2\dotsb$,$100)$中$S_{0}=S_{5}=0$, $S_{2}=S_{3}=-3d$,$S_{1}=S_{4}=-2d$, 其余各项均不相等, $\therefore S_{i}(i=0$,1,$2\dotsb$,$100)$中不同的数值有:$101-3=98$. 故答案为:98. 点评:本题考查等差数列的前$n$项和公式、通项公式等基础知识,考查运算求解能力,是中档题.
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