等比数列教学申关于公比qfi三个“目点”：0，士1；这三个“喜点”蛤经伴随着公比，不论是命题还是解题，稍有不慎，就会不知不觉地陷人尴尬的确地．“各点”1：公比q士0．这是决定公比的自要条件．在教学中可设计下面几个例子来明晰概急．例ig数列｛a。｝的前n顶和S。一b”一1 The number of teachings in the equals is about the three “goals” of the public ratio qfi: 0, 1; the three “hi” points are accompanied by the public ratios, whether they are propositions or problem-solving. He is unaware of the fact that he is really ignorant. “All points” 1: Public ratio q. This is a self-inflicted condition that determines the public ratio. In the teaching, the following examples can be designed to clarify the urgency. Example ig sequence {a. } Top n top and S. One b" to one