Question

Which function has an inverse that is also a function?
{(–4, 3), (–2, 7), (–1, 0), (4, –3), (11, –7)}
{(–4, 6), (–2, 2), (–1, 6), (4, 2), (11, 2)}
{(–4, 5), (–2, 9), (–1, 8), (4, 8), (11, 4)}
{(–4, 4), (–2, –1), (–1, 0), (4, 1), (11, 1)}

Answer 1

The first set: {(–4, 3), (–2, 7), (–1, 0), (4, –3), (11, –7)}.

Reason: its outputs (3, 7, 0, −3, −7) are all distinct, so the function is one-to-one and its inverse is a function. The other sets have repeated y-values, so their inverses would not be functions.