Question

look at this table:

x	y
-20	15
16	-4
-1	5
9	0

is this relation a function?
yes no

Explanation:

A relation is a function if every input (x-value) has exactly one unique output (y-value). Checking the table, each x-value (3, -20, 16, -1, 9) maps to only one y-value with no repeated x-values.

Answer:

yes