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对课本中的一些例、习题进行变式,使之貌似原题,又不同于原题,利用这种变式训练,有利于培养同学们思维的变通性、灵活性和深刻性．题目(新教材第一册(上))解不等式2x2 -3x-2>0．思考1改变二次项系数的符号．变式1解不等式-2x2+3x+2>0．分析本题中x2项系数出现了负数,应先将x2项的系数化正,故原不等式可化为2x2- 3x-2<0,解得-1/20．分析本题中一次项系数出现了字母,故应讨论判别式的符号．
Some variations of textbook examples and exercises are made to look like the original question and different from the original question. Using this variant training will help cultivate the flexibility, flexibility and understanding of the students’ thinking. Title (New Book One (I)) Solution Inequality 2x2 -3x-2>0. Think 1 change the sign of the quadratic coefficient. Variant 1 solution inequality -2x2+3x+2>0. Analysis of this item in the x2 coefficient has a negative number, should first x2 coefficient of the positive, so the original inequality can be turned into 2x2 - 3x-2 <0, the solution was -1/2 0. Analysis of this item in the first item coefficient appears letters, it should discuss the discriminant symbol.