1. Let a and b be non-empty number sets. If any number in set A has a unique number corresponding to it in set B according to a certain correspondence, it is called a function from set A to set B, and it is recorded as:

2. The constituent elements of a function are: definition domain, correspondence domain and value domain. If two functions have the same domain and the same correspondence, they are said to be equal.

1.2.2, the representation of the function

1, there are three ways to express the function: analytical method, image method and list method.

1.3. 1, monotonicity and maximum (minimum) value

1, pay attention to the general format of function monotonicity proof:

1.3.2, parity

1. Generally speaking, if there is any one in the domain of a function, then the function is called an even function. Even function images are symmetric about axis.

2. Generally speaking, if there is any one in the domain of a function, then this function is called odd function-odd function's image symmetry about the origin.

Chapter 2, Basic Elementary Functions (Ⅰ)

2. 1. 1, exponential and exponential power operations

1, generally speaking, if, then it is called the second root. One of them is.

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