Factor 9b 2 - 4.
O (3b + 1)(3b - 4)
O (3b + 2)(3b - 2)
O (3b - 2)(3b - 2)
O (3b + 1)(3b - 4)
O (3b + 2)(3b - 2)
O (3b - 2)(3b - 2)