1,2,3,4……100.一百个数中任取三个数构成等差数列的概率
问题描述：
1,2,3,4……100.一百个数中任取三个数构成等差数列的概率
答
100个数中取3个数共有100*99*98/(3*2*1)=1617设取得的等差数列公差为d当d=1时,有100-2=98种取法当d=2时,有2*（50-2）=96种取法·········································...