Function was actually talked about in junior high school, of course, it was the simplest primary school and middle school at that time, and the most dramatic function of the whole high school function was actually the middle school function. The general strategy of learning functions well is to master the nature of each function, so that it can be used freely and prepared. The properties of functions are monotonicity, parity, boundedness and periodicity. The only functions that can perfectly embody the above properties are sine function and cosine function in middle school trigonometric function. These are the basic properties of functions. Symmetry can be derived from parity, which is related to quadratic function. In fact, quadratic function can be associated with all the above properties, and any function can, because these properties are abstracted from a large number of basic functions, so as to describe them more vividly. I'm sure you have a deep understanding of this. The remaining power functions, exponential functions, logarithmic functions and so on are not complicated in themselves. As long as we grasp the properties, such as the definition domain of logarithmic function and the value domain of exponential function, the questioner can make a big fuss and the respondent can swim in it. Nature is the most essential thing of function, and the essence of the world is simplicity. Complexity is only an external manifestation, and function can well reflect this. In addition, you have to learn derivatives in senior three. Learning well can help you understand the things ahead, while learning badly will disturb people's thinking. Therefore, I suggest you preview, because preview will never let you fall behind. My core learning experience is preview, which makes me far ahead of other students in mathematics and invincible.
To sum up, in the process of learning the function, we should grasp its nature and preview the feedback to the learning method (it is best to learn by yourself if you have the ability).