First of all, we should remember several commonly used derivative formulas clearly; Then look at the definition domain first when solving the problem; Derive the function and divide the result; Next, in general, let the derivative =0 and find the extreme point; Judging whether the sign of the derivative is positive or negative in the interval on both sides of the extreme point; If it is positive, the original function will increase, if it is negative, it will decrease. Then according to the increase or decrease, you can roughly draw the image of the original function, and you can find out what you want according to the image, such as the maximum or minimum. In special cases, the sign of the derivative itself can be directly determined, that is, when the derivative is equal to 0 and there is no solution, it shows that the original function is monotonous in the whole section. If the derivative is always greater than 0, it will increase; On the contrary, it will decrease. Whether it is a big problem, a small problem or an application problem, it is this routine.