Generally speaking, the mild derivative problem will set such a problem in the first problem: if f(x) takes the extreme value when x = k, try to find the value of the parameter in the given function; Or the tangent of f(x) at (a, f(a)) is perpendicular to a known straight line, and try to find the values of parameters in a given function and many other conditions. Although there are many tricks, it is easy to solve them as long as you understand that their essence is to examine everyone's ability to find derivatives. This is generally used to distribute points, so you must be calm when encountering such problems. The method is:

First, find the derivative function of a given function, and then take the above-mentioned first case as an example by using the known conditions given in the title: let x = k and the derivative of f(x) be zero, find the value of the parameters contained in the function, and then check whether it is the extreme value of the function at this time.

Note: the derivative function must not be wrong, otherwise not only the first question will fail, but also the whole question will fail. The best way to make sure you don't make mistakes in the derivation is not to be too fast, but to be careful. In addition, the derivative formula should be firmly remembered and not sloppy. When you encounter the situation in the example, you should remember to take the test together, especially when you solve two solutions, otherwise there may be more solutions, resulting in points deduction and losses.

So the way to sum up this kind of problem in two words is: calm down. Don't mention it when others give it to you. When finding the tangent, it depends on whether the given point is on the function. If not, you need to set a tangent point and then solve it. Tangents should be written as general expressions.