Question

(04.01 LC)
Which of the tables represents a function?
Table A

Input: 4, 5, 4,
Output: 2,9,7,

Table B

Input: 9,9,7,
Output: 2,3,5,

Table C

Input: 4,6,2,
Output: 3,5,7,

Table D

Input: 8,6,8,
Output: 7,5,5,

A) Table A
B) Table B
C) Table C
D) Table D

Answer 1

Answer: Table C

With tables A, B and D, we have repeated input (x) values.

Table A has x = 4 repeated. So the input x = 4 leads to both outputs y = 2 and y = 7 at the same time. With any function, we must have exactly one and only one output for any given input. So this is why table A is not a function. Tables B and D are not functions for similar reasons.

Table C on the other hand has unique inputs that do not repeat. The input x = 4 only leads to y = 3, x = 6 pairs with y = 5, and x = 2 outputs to y = 7. Therefore we have a function here.