关于求函数自变量取值范围是学生必须掌握的知识点之一 ,为更好地学好这一知识点 ,应注意以下四方面。一、注意“且”与“或”的用法例 1　求函数 y =1x2 -x - 2 取值范围。错解 :要使函数有意义 ,x必须满足x2 -x - 2≠ 0 ,即 (x +1 ) (x - 2 )≠ 0则x + 1≠ 0得x≠ - 1 ,或x - It is one of the knowledge points that students must master to find the value range of the function’s independent variables. To better learn this knowledge point, the following four aspects should be noted. First, pay attention to the use of “and” and “or” 1 Find function y = 1x2 -x - 2 range of values. Misunderstanding: To make the function meaningful, x must satisfy x2 -x - 2≠ 0, that is (x +1) (x - 2 )≠ 0 then x + 1≠ 0 gets x≠ -1, or x -