Question

Which relation is a function?

A.
{(–5, 1), (4, 9), (6, 10)}

B.
{(0, 3), (0, 9), (12, –4)}

C.
{(5, 5), (5, 9), (5, 15)}

D.
{–2, 10), (–6, 10), (–2, 3)}

Answer 1

By definition, a function is when one input (x) maps out to one output (y).

Only the first set of points meets this condition

The second set of points, x = 0 maps out to both y= 3 and 9 so it cannot be a function.

The third set of points, x = 5 maps out to y = 5 and 9 so it cannot be a function.

The fourth set of points, x=-2 maps out to y = 10 and 3 so it cannot be a function.