Here's the question you clicked on:
why.math
The domain of the following relation: R: {(3, −2), (1, 2), (−1, −4), (−1, 2)} is {−1, 1, 3} {−1, −1, 1, 3} {−4, −2, 2, 2} {−4, −2, 2}
no duplicates needed so 2 and 3 are out
-4 aint a first number so 4 is out
1 and 2 are actually equal and equivalent; but for "proper" notation its 1
thank you for explaining