Say whether or not f(x) is defined for the given values of x. If it is defined, give its value. HINT [See Quick Example 3.] (If an answer is undefined, enter UNDEFINED.)
f(x) = 16 - x^2, with domain (-4, 4)
(a) x = 0
f(0) =
(b) x = 4
f(4) =
(c) x = -4
f(-4) =