Is it a function? Ordered pairs

A relation is a function if every x-value has exactly one y-value. Write yes or no.

1. Is this set of ordered pairs a function? (−5, 2), (−5, 1), (2, −4), (3, 1), (6, −6). Write yes or no.
2. Is this set of ordered pairs a function? (3, 3), (−5, −1), (−5, 0), (2, 3), (−1, 4). Write yes or no.
3. Is this set of ordered pairs a function? (−5, −6), (6, −6), (2, −1), (−5, 2), (−3, −6). Write yes or no.
4. Is this set of ordered pairs a function? (−4, 6), (6, −4), (−1, 1), (3, −5), (−1, 5). Write yes or no.
5. Is this set of ordered pairs a function? (5, 1), (3, 5), (4, 4), (7, 6), (−7, 0). Write yes or no.
6. Is this set of ordered pairs a function? (0, 2), (3, 8), (7, 5), (5, 5), (3, −7), (−6, −7). Write yes or no.
7. Is this set of ordered pairs a function? (−3, 8), (−8, −2), (6, −7), (−7, −1), (4, 3), (−3, −1). Write yes or no.
8. Is this set of ordered pairs a function? (−2, 5), (5, −7), (1, 3), (1, −1), (−1, −3), (0, −2). Write yes or no.
9. Is this set of ordered pairs a function? (−4, 2), (−8, 7), (−6, 10), (−2, 2), (−1, 3), (9, −4). Write yes or no.
10. Is this set of ordered pairs a function? (−3, 0), (−2, −6), (−4, −4), (0, −4), (−8, −10), (7, 0). Write yes or no.
11. Is this set of ordered pairs a function? (8, −5), (6, 1), (5, 6), (3, −2), (3, 10), (−7, −6), (−2, −10). Write yes or no.
12. Is this set of ordered pairs a function? (−5, 8), (6, −1), (9, 3), (−10, 7), (−4, 2), (1, 7). Write yes or no.
13. Is this set of ordered pairs a function? (0, 3), (−8, −6), (−10, −10), (11, −12), (−11, −11), (−10, −5), (−5, −2), (10, 5). Write yes or no.
14. Is this set of ordered pairs a function? (−1, −12), (−10, −1), (12, −9), (−3, 4), (−1, 0), (8, 11), (4, −6), (−6, 7). Write yes or no.
15. Is this set of ordered pairs a function? (−3, 1), (5, −12), (6, 1), (−6, 0), (7, −11), (−5, −3), (4, −5). Write yes or no.
16. Is this set of ordered pairs a function? (9, 0), (−2, −10), (−8, 4), (−1, −5), (−4, 9), (7, −8), (9, 1), (−10, 11). Write yes or no.
17. Is this set of ordered pairs a function? (3, 5), (−5, 15), (−12, −2), (3, 4), (1, −1), (5, −11), (6, −11), (−11, −3), (−8, −1). Write yes or no.
18. Is this set of ordered pairs a function? (−3, 3), (15, 10), (−14, −9), (8, −3), (1, −13), (−6, 3), (11, 4), (7, 9). Write yes or no.
19. Is this set of ordered pairs a function? (13, 1), (1, −14), (−10, 13), (−1, 13), (−8, 11), (−14, 2), (0, 10), (−7, −4). Write yes or no.
20. Is this set of ordered pairs a function? (3, −1), (−4, 12), (−10, 12), (5, −5), (−2, −10), (6, −9), (8, −3), (4, −8), (5, 8). Write yes or no.