Question

Which relation is a function?

A. (–25, 16), (0, 16), (–25, 18)

B. (19, 11), (34, 12), (34, 10)

C. (35, 31), (24, 15), (12, 0)

D. (34, 30), (18, 17), (34, 15)

Answer 1

To answer this question, we need to know how "functions" are defined. A "function" is a rule that assigns a y-value to each x-value. For example, y=2x is a function; for any given x-value, we can calculate the corresponding y-value, and there is ONLY ONE y-value for each x-value.

Look at "D" strictly as an example: D. (34, 30), (18, 17), (34, 15).

Does this set of points pass or fail the rule that "there is ONLY ONE y-value for each x-value?"