Question

3. Marianne explained that the set of ordered

pairs below does not represent a function
because each input has the same output. Do
you agree? Explain.
{(9, 1), (10, 1), (11, 1), (12, 1), (13, 1))

Answer 1

Answer: Disagree; it is a function

Reason

Each of the x coordinates 9, 10, 11, 12, 13 are listed once. We don't have any repeated x values mentioned more than once.

If we had something like (9,1) and (9,2), then we won't have a function. Recall a function is when each input x maps to exactly one and only one y output. This must mean repeated x values aren't allowed.

Repeated y values can be allowed in functions; however, the function won't be one-to-one.

In this function, it appears to be a horizontal line through y = 1.

Visually you can plot all of those points. Then notice how the set of points passes the vertical line test. This is a quick visual way to see that we have a function.