Question

(1) Which of the following is a function? O {(2,5), (5, 2), (0, 0)} {2, 5, -9,0} *** ******* O {(2, 5), (-9, 0), (-9, 2), (0, -9)} O {(2, 5), (5, -9), (2, 0)} N.

Answer 1

We need to have a set of ordered pairs such that for each element in the first coordinate there is only one element in the second coordinate. Then, the set

$\mleft\lbrace(2,5\mright),(5,2),(0,0)\}$

is a function, but the others are not since

$\mleft\lbrace2,5,-9,0\mright\rbrace$

are not ordered pairs and in the third and fourth options, the numbers -9 and 2 are repeated, respectively.