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排列组合问题是学习的难点,高考的重点,今举例说明求解排列组合问题的常用策略.一、特殊元素、特殊位置优先安排策略对于存在特殊元素或特殊位置的排列组合问题,可以从这些“特殊”入手,先满足特殊元素或特殊位置,再满足其他元素或位置.例1(2008陕西高考)某地奥运火炬接力传递路线共分6段,传递活动分别由6名火炬手完成.如果第一棒火炬手只能从甲、乙、丙三人中产生,最后一棒只能从甲,乙两人中产生,则
Arranging combinatorial questions is the difficulty of learning, the focus of the entrance exam, this example illustrates the common strategy for solving the combination of the combination of problems.One, special elements, special location prioritization strategyFor the existence of special elements or special location permutations and combinations, from these “ Special ”to start with, to meet the special elements or special locations, and then meet other elements or locations .Example 1 (2008 Shaanxi college entrance examination) a Olympic torch relay route is divided into 6 segments, the transfer activities were completed by six torchbearers if The first torch bearer only from A, B, C trio, the last stick only from A, B two people, then