Which of the following functions f has a removable discontinuity at a? If the discontinuity is removable, find a function g that agrees with f for x ≠ a and is continuous at a.
(a) f(x) = x4 - 1/ x -1, a = 1
(b) f(x) = x3 - x2 - 2x / x - 2, a = 2
(c) f(x) = [sin x], a = π