论文部分内容阅读
问题222刊出后,来稿雪片似地飞来,至截稿时止,共收稿51篇.带有倾向性的意见是:原解法1错误;解法2虽然结果正确,但推理存在逻辑错误.原解法1在得出结果后,对其合理性未进行检验(这是G·波利亚在“解题表”中“反思”部分的内容之一).检验,学生一般以为是再核算一次,以杜绝因粗心所造成的失误,其实,更重要的是审视解答结果的合理性(包括是否符合实际).事实上,充分挖掘题目条件,可知sinA的最大值取不到1,以致得出了错误结果还全然不知;解法2中由AB~2+AC~2≥50不能推出AB·AC≥25,反过来才是成立的,即颠倒了逻辑顺序.
After the issue of 222 was published, the draft came flying like a piece of paper, until the deadline, received a total of 51. With a bias of opinion is: the original solution a mistake; Solution 2 Although the result is correct, but there is a logical error reasoning. Solution 1 After the result has been obtained, its rationality is not tested (this is one of G. Pollia’s contents in the section entitled “Reflection” in the “Problem Solving Table”). In fact, to fully tap the topic conditions, we can see that the maximum value of sinA can not be less than 1, So that the result of the error is still completely unknown; solution 2 by AB ~ 2 + AC ~ 2 ≥ 50 can not be introduced AB · AC ≥ 25, the reverse is true, that is, reversed the logical order.