The correct option is B 3x+14(3x+4)
3x2−x−49x2−16÷4x2−43x2−2x−1
= 3x2−x−49x2−16×3x2−2x−14x2−4
= 3x2+3x −4x−4(3x)2−(4)2×3x2−3x +x −14(x2−1)
= 3x (x+1) −4 (x+1)(3x +4) (3x− 4)×3x (x − 1) +1 (x −1)4 (x−1) (x + 1)
= (3x−4) (x+1) (3x+1) (x−1)4 (3x+4) (3x−4) (x−1)(x+1)
= 3x+14(3x+4)