F (x) = { (1, 4), (2,3), (5,8), (4,7) } Is f^-1 (x) a function and why?

f (x) = (1, 4) (2, 3) (5, 8) (4, 7)

f-1 (x) = (4, 1) (3, 2) (8,5) (7,4)

For any given x in the domain of f-1 (x) there is one and only

one value y in the range of f-1 (x) ... Thus, f-1 (x) passes the

vertical line test and is a function.