If there is f (x[0]) ≥ f (x) near x[0], then x [0] is the maximum point (if it is less than or equal to the sign, it is the minimum point), and if it becomes strictly greater than or less than the sign, it is the strict maximum or minimum point.

The image of the function f(x)=c is a straight line y=0. In other words, a literal function is a function whose range contains only one element. That is to say, for all x's within the definition domain of this function, there is f(x)=a, where a is a fixed element.

Constant function has extreme points, and each point is an extreme point, which is both a maximum point and a minimum point (it is easy to get according to the definition, which is the case when the equal sign is established).

Extended data:

Brief introduction of periodic function

definition

If a function has a constant such that f(x+T) = f(x), the function is called a periodic function, and t is called the period of the function.

Property 1: If t is an arbitrary period of a function, then the inverse of t (-T) is also a period.

Property 2: If t is the period of a function, then nT is also the period of any integer n(n≠0).

Property 3: We call a positive number the positive period of a function and a negative number the negative period of a function. If there is a minimum positive period among all positive periods, we call it the minimum positive period of the function, and write it as T*.

Supplement: Constant function has no monotonicity.

Baidu Encyclopedia-Constant Function