What equation describes the connection between x and y in the relation {(1, 3), (5, 7)}? Is it a function?
y = x + 2
Yep, it's a function. A relation is a function if each thing in the domain gets paired with only one thing from the range. Another way to think of it is that each x-value gets matched with only one y-value. You can only bring one partner to this square dance.