HELP!!

Look at these sets of ordered pairs.
W) {(8, 9), (2, 3), (0, -2), (10, -9)}
X) {(0, 0), (5, 10), (-3, 3)}
Y) {(1, 1), (2, 2), (3, 3), (4, 4)}
Z) {(-10, 1), (-9, 3), (-4, 5)}
Which of the sets represent functions?

Question

HELP!! 

Look at these sets of ordered pairs.
W) {(8, 9), (2, 3), (0, -2), (10, -9)}
X) {(0, 0), (5, 10), (-3, 3)}
Y) {(1, 1), (2, 2), (3, 3), (4, 4)}
Z) {(-10, 1), (-9, 3), (-4, 5)}
Which of the sets represent functions?

anonymous · Answer

the ones where there is no repeat in the first coordinate of each ordered pair

anonymous · Answer

would that be W,Z?

anonymous · Answer

for example $\{(8, 9), (2, 3), (0, -2), (10, -9)\}$ IS a function because
 8, 2, 0 ,10 are all different

anonymous · Answer

how about $ \{(0, 0), (5, 10), (-3, 3)\}$?  
the first numbers are 0,5,-3
any repeats there?

anonymous · Answer

Yes. 0

anonymous · Answer

look carefully at the first numbers
completely ignore the second numbers

anonymous · Answer

first numbers are  0,5,-3
they are all different, right?

anonymous · Answer

yes

anonymous · Answer

then it IS a function
it has nothing whatsoever to do with the second numbers, only the first ones

anonymous · Answer

so it will be X