(2) The number corresponding to x=2 in B is 4.

(3) The number corresponding to Y=9 in A is A 3,3.

3.f(0)= 1 3, f(2)= 1, f(5)=7, and the range of values is {1 3, 1,13.

4. D. Tip: Only when the domain and corresponding rules of two functions are exactly the same, they are the same.

Function, and the definition domains of the two functions in options A, B and C are different, so they are not the same function. only

The definition fields and corresponding rules of the two functions in option D are the same, so they are the same function.

5.( 1) both the domain and the value domain are r.

(2) The domain is {x∣x∈R and x≠0}, and the range is {{y∣y∈R and y ≠ 0}.

(3) both the domain and the value domain are r 。

(4) The domain is R, because y=(x-3)2-2, so the value range is [1-2, +∞).

Their images are abbreviated.

6. The domain of (1) is {x∣x∈R, x≠ 1, x≠2}.

(2) The domain is [14, -2]∨( 2, +∞)

(3) The domain is (2/3, +∞)

(4) The domain is (1/3, 1/2).

(5) The domain is [3, +∞) ∨ (an∞, a 3).

[6] The domain is [1 2, 1]∨( 1, 2].

Step 7 omit

8.( 1), (2) and (4) represent the mapping from set a to set b, because any one of set a.

Each element in B has a unique element corresponding to it.

(3) The representation is not a mapping from A to B, because the element in A is a3, and b 1 in B,

B3 corresponds to it.