Which of the following does NOT represent a one-to-one correspondence between x and y?

Question

A)

x y
0 0
1 1
2 0
3 1
4 0

B)

x y
0 0
1 1
2 -2
3 3
4 -4

C)
x y
0 0
1 1
2 4
3 9
4 16

D)

x y
0 1
2 3
4 5
6 7
8 9


I think its C, but not sure!

Answer 1

A

CASE B)
x y
0 0
1 1
2 -2
3 3
4 -4

x = y

CASE C)
x y
0 0
1 1
2 4
3 9
4 16

x * x = y

CASE D)

x y
0 1
2 3
4 5
6 7
8 9

x + 1 = y

CASE A) is the only one without any relationship

Answer 2

Hi,
Well, if a functions has no two ordered pairs with first coordinates, x for example, and the same second coordinate; then the function is one-to-one.
So, if we look at A) we have (1,1) and (3, 1). So, since they have the same value of y, this is not one-to-one.

Hope this helps.
FE