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问题有一人患了流感,经过两轮传染后共有121人患了流感,每轮传染中,平均一人传染了几个人?解题指导:这是人教版九年级数学上册第45页的一道探究题,属于连续增长类型的实际应用题,这类问题也是近年中考的热点.(1)基本量是:期初数、期末数、增长率.基本关系:期末数=期初数×(1+增长率).(2)在增长率问题中关键量是“增长率”.对于连续增长,增长率是相同的(平均增长率),连续两次增长后,期末数=期初数×(1+平均增长率)~2.增长率问题还包括负增长的情况,如降价.事实
The problem of a person suffering from the flu, after two rounds of infection, a total of 121 people suffering from the flu, each round of infection, the average person infected with a few people? Problem-solving guide: This is the PEP ninth graders on page 45 of a study (1) The basic quantity is: the beginning of the period, the end of the period, the growth rate. Basic relations: the number of the end of the period = the beginning of the period × (1 + growth rate (2) The key measure of growth rate is “growth rate.” The growth rate is the same for continuous growth (average growth rate) Average growth rate) ~ 2. The issue of growth rate also includes the case of negative growth, such as price cuts.