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中学数学2003年第7期刊登了胡兴平老师的“一道关于传球问题的解法探究”.下面介绍这道题的一种更简单而通俗且便于课堂教学的解法——抓两头促中间法. 题目 三人传球由甲开始发球,并作第一次传球.经5次传球后.球仍回到甲手中,则不同的传球方法共有( ). (A)6种 (B)8种 (C)10种 (D)16种 分析 由于球开始和最后都在甲手上.四此球第一次传出后及最后一次传出前必须在“非”甲手上(为了方便,把乙和丙统称为
In middle school mathematics, the 7th issue of 2003, published by Hu Xingping, “An Inquiry into the Problem of Solving Passing Problems.” Here is a simpler, more general, and easy way to solve the problem of classroom teaching. The three players pass the ball from A to serve the first pass. After 5 passes, the ball is still returned to A. The different passing methods are total (). (A) 6 (B) 8 The (C) 10 species (D) 16 kinds of analysis are due to the start and the end of the ball in the hand. 4 This ball must be on the “non-” hand after the first pass and the last pass (for convenience, The B and C groups are called