I think you should still be a high school student now. I said some of my own opinions, which may be different from what the teacher taught me. High school should only learn elementary functions. According to my method, elementary functions are divided into three categories: 1. Basic elementary functions, including power, finger, pair, triangle and anti-triangle (some people regard polynomial functions as basic elementary functions, but I am not like this, which will be mentioned below); Exponential function is y = a x, base is constant, and exponent is independent variable. The power function is y = x a, the exponent is constant, and the base is an independent variable. Power function and exponential function must be clearly understood and cannot be confused! ! The new contact of logarithmic function will be embarrassing. You just think that the function value is the exponent of the power, the logarithmic base is also the base of the power, and the real number (the independent variable of the logarithmic function) is the value of the power. Do more questions for the rest, just be skilled. 2. The linear combination of basic elementary functions is that several different basic elementary functions are multiplied by a coefficient and then added and subtracted. Polynomial function can be considered as a linear combination of several power functions. 3. The combination of the above two types of functions. The so-called synthesis is to bring the expression of y of one function into x of another function, for example, y = (ln (x)) 2, which can be considered as the synthesis of y=ln(x) into y = x 2. Any elementary function can be obtained through these three steps. For example, y = ln (3x 2+e x+2) can be understood as follows: firstly, the power function y = x 2, exponential function y = e x and power function y = x 0 are linearly combined (multiplied by the coefficients 3, 1, 2 respectively). After mastering this theory, you can learn the function of senior high school according to this idea: 1. Learn the properties of basic elementary functions (definition range, range, monotonicity, parity, periodicity, derivative solution, etc.). ), listen carefully in class and get enough training to be proficient. 2. Master some properties of known basic functions and related properties of functions obtained by their linear combination. 3. Master some properties of two known functions and related properties of their composite functions. Many high school students study mathematical functions, such as monotonicity and parity. , along this routine, especially the derivative part. If you don't have a clear idea, you don't know what you learned after dinner.