## 伍鸿熙对因式分解及分式化简教学的一点看法

There is no denying that beginning students ought to acquire some facility with decomposing numbers into products. It is also important that they can e ortlessly factor a simple quadratic polynomial $x^2+2x-35$ as $(x+7)(x-5)$. But it sometimes happens that if a little bit of something is good, a lot of it can actually be bad for you. This seems to be the case here, when the teaching of a small skill gets blown up to be a major topic, with the consequence that other topics that are more central and more substantial (such as learning about the graphs of linear equations or solving rate problems correctly) get slighted. The teaching of algebra should avoid this pitfall. Please also keep in mind the fact that once the quadratic formula becomes available (see Section 12), there will be a two-step algorithm to accomplish this factorization no matter what the coefficients of the quadratic polynomial may be.

In beginning algebra, often there is too much emphasis on simplifying rational expressions. This is a left-over from the questionable practice of teaching fractions by insisting on the reduction of all fractions to lowest terms at all costs.

posted on 2016-08-06 23:44  星空暗流  阅读(...)  评论(...编辑  收藏