The correct option is B (x−4)3(3x+1)
Factor the numerator: 6x2 -21x - 12 = 3(2x2 - 7x - 4) = 3(x - 4)(2x + 1)
Factor the denominator: 54x2 +45x + 9 = 9(6x2 + 5x + 1) = 9(3x + 1)(2x + 1).
∴6x2−21x−1254x2+45x+9=3(x−4)(2x+1)9(3x+1)(2x+1)
Cancelling out common factors,
= (x−4)3(3x+1)