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现行九年制义务教育小学数学教材在介绍乘法运算各部分之间的关系时,都先出示乘法运算的基本关系式,再通过一个具体的乘法算式直接推导出另一个除法关系式。如浙教版《数学》第八册第39页是这样推导的: 因数×因数=积……①从左面可以知道:一个因数=积;另一个因数……②笔者认为,教材在由关系式①推导得出关系式②时,犯了以偏概全的错误。因为在关系式①中,“因数”和“积”无任何条件限制,但当其中的一个“因数”等于零时,关系式
Current nine-year compulsory education in primary school mathematics textbooks to introduce the relationship between the various parts of the multiplication operation, first show the basic formula for multiplication, and then through a specific multiplication formula directly derived another division relationship. Such as the Zhejiang version of “mathematics” eighth book page 39 is derived as follows: factor × factor = product ... ... ① From the left you can know: a factor = product; another factor ... ... ② I believe that textbooks in the relationship ① deduced the relationship between ②, made a general error. Because in the relationship ①, “factor” and “product” without any restrictions, but when one of the “factor” is equal to zero, the relationship