对于已知自变量的取值范围的不等式恒成立问题,是不等式中重要的题型,也是各类考试的热点。不等式中既含有参数,又有变量,学生往往感到难以下手。通常可借助相应函数的单调性求解。主要技巧有:数形结合法、分离变量法、主元法等方法。 The problem of inequality constant establishment for the range of known independent variables is an important type of problem in inequality, and it is also a hot spot for various examinations. Inequalities contain both parameters and variables, and students often find it difficult to start. It is usually solved by the monotonicity of the corresponding function. The main techniques are: number combination method, separation variable method, principal component method and other methods.