Compound function is composed of more than two basic elementary functions (such as linear function, quadratic function, exponential function, etc.). ).

Let's give a concise example:

F(x)=ln(2x+ 1) consists of two functions, y=lnu and u=2x+ 1. When taking derivative, you can multiply the derivative results of two formulas. First of all, we should memorize the derivative formula of the basic elementary function, and then we can get y' = 1/u, u' = from this problem.

Finally, remember to bring the set u back to the original function, that is, f'(x)=2/2x+ 1.

Note that a composite function is different from the product of two functions. If it is changed to lnx*2x+ 1, the result will be completely different (note the difference between them, the two functions of the composite function are a whole, and the product is the product of the two functions), and the derivative operation rule (derivative function * original function+original function * derivative function) should be used.

I wish you progress in your study and hope to adopt it.