函数单调性是函数的重要性质之一,从代数意义上看,函数的单调性反映了函数值随着自变量的增大而变化(增大或减小)的情况;从几何意义上来看,函数的单调性反映了函数图像在定义域的各个子集内的变化情况(上升或下降).因此函数的单调性是研究函数运动变化趋势的重要内容和方法. Function monotonicity is one of the important properties of the function. From the viewpoint of algebraicity, the monotonicity of the function reflects the fact that the function value changes (increases or decreases) with the increase of the independent variable; from a geometrical point of view, The monotonicity of the function reflects the change (rising or falling) of the function image in each subset of the domain. Therefore, the monotonicity of the function is an important content and method for studying the trend of function movement.