题目内容：

Given the domain,D={-1,0,1},which equation represents a function?
A:y²=x² B:x²+y²=25 C:y=1／x D:y=﹣x²
1.This problem need you to test out several points such as D for { -1,0,1}.
2.Example,when you plot coordinate points of ( X,Y) such that (1,-1),(2,0),( 3,1) which
answer choice in A,B,C or D would create something that look for like a line graph?
3.When you are able to figure this out,then you found the answer.

优质解答

A,C,D
A存在定义区间内的点(x=0,y=0),(1,1)(1,-1)(-1,-1)(-1,1)
C存在(1,1)(-1,-1)
D存在(1,-1)(0,0)

追问：

忘记说了~这是选择题~

追答：

A,C,D 都是正确的

追问：

那最好选哪个？

追答：

。。。A，唯一的不同就是A的函数在整个区间内有意义， CD都是部分有意义