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一、从思维的条件来说数学中常用一题多变,一题多编的形式,培养思维的变通性。具体说来,要求对问题中所给予的条件,善于分析、解译、重新组合、变换或增减。 1.充分条件判断指有了这一条件,一定会有某种结果(有之必然):没有这一条件,不一定没有这个结果(无之未必不然)。例如,从北京到乌鲁木齐航行需3.5小时,而从乌鲁木齐到北京却只需3个小时,这是因为:“中纬度上空西风的影响”(四个选答项之一)。西风是此题的充分条件,有了它,促使由西向东航行加快;如果没有它,而有其它原因也可能会使航行加快。 2.必要条件判断指没有这一条件,一定不
First, from the condition of thinking, mathematics is often used in a variety of topics, a multi-educational format to cultivate the flexibility of thinking. Specifically speaking, it is required to be good at analyzing, interpreting, regrouping, changing, or increasing or decreasing the conditions given in the question. 1. Sufficient conditional judgment means that with this condition, there must be some result (necessary): Without this condition, this result is not necessarily absent (nothing is not necessary). For example, it takes 3.5 hours to fly from Beijing to Urumqi, but only 3 hours from Urumqi to Beijing because of: “The influence of the westerlies over mid-latitudes” (one of the four options). The West Wind is a sufficient condition for this question. With it, it will prompt the voyage from west to east; without it, other reasons may also make the voyage faster. 2. The conditional judgement means that there is no such condition, certainly not