对于某些附带条件的代数式取值范围的数学问题,由于条件的内隐性较强,同学们在解决这类问题过程中,往往容易产生一些似是而非的解法,而且在误解产生后,常常不易被自己所察觉.本文试图通过对一个典型的例子的几种误解的剖析,以期引起同学们对这类问题解法的关注. For some mathematical problems with algebraic range of conditions with certain conditions, because of the highly implicit nature of the conditions, students in the process of solving such problems are often prone to produce plausible solutions, and after the occurrence of misunderstandings, they are often difficult to be It has been noticed by myself. This article attempts to analyze the misunderstandings of a typical example, in order to arouse students’ attention to the solution to this type of problem.