我们在学习函数单调性时应倍感亲切,因为初中时已经接触过.当时有两句口诀人人都会讲,第一句:“y随x增大而增大”.这就是高中所学的增函数.第二句:“y随x增大而减小.”这就是减函数.当时没有点明函数的单调性,也没有强调单调区间,进入高中后学习函数单调性时,将上述两句语言抽象成了数学符 When we learn the monotony of the function should be more cordial, because the junior high school has been exposed .There are two formulas everyone will say, the first sentence: “y increases with x increases.” This is the high school The second sentence: “y decreases as x increases. ” This is the reduced function. At that time did not point out the monotony of the function, did not emphasize the monotonous range, monotonous when entering the high school after learning function , The above two language abstractions into mathematical symbols