contestada

(2,1), (3,4), (5,6), (2, 7) - (3,1), (−3, 1), (0,1), (5,1) - (1,1), (2,2), (3,3), (4,4) - (4,1), (6, 7), (8, 9), (4,7)- (2,4), (2,5), (2,6), (2,8) which ones are function or no function.