1.“单调性概念理解”的严谨性缺失书本定义:设定义在某区间上的函数y=f(x),如果f’(x)>0,那么函数y=f(x)在这个区间内单调递增;如果f’(x)<0,那么函数y=f(x)在这个区间内单调递减.理解这正是我们同学用来解决求函数单调区间的依据,但同学们往往忽略了这只是函数在这个区间上单调递增或递减的一个充分条件,而并非必要条件. 1. The definition of monotonic lack of rigor in the concept of understanding The definition of the book: set the function defined in a range of y = f (x), if f ’(x)> 0, then the function y = f This interval monotonically increases; if f ’(x) <0, the function y = f (x) decreases monotonically in this interval. Understanding This is exactly what our classmates used to solve the monotonic interval of the function, but students often Ignoring this is just a sufficient but not necessary condition for the function to monotonically increase or decrease over this interval.