在已设定的单调区间上证明函数的单调性是大家熟悉的，而当给定函数的定义域（或指定区间）不是单调区间时，如何确定单调区间的端点，进而确定其单调性却没有现成的路可走，这里试给出一种确定单调性的方法，估且称其为“零点法”，具体步骤是：在函数ｆ（ｘ）的定义域内... It is well known that the monotonicity of a function is known in a monotonic interval that has been set, and when the domain (or specified interval) of a given function is not a monotonous interval, how to determine the endpoint of a monotonic interval and thus determine its monotonicity is not The ready-made road can go, here try to determine a method to determine monotonicity, estimate and call it “zero point method”, the specific steps are: in the domain of function f (x)...