Expand and simplify: (2x−1)(x+4)(2x - 1)(x + 4)(2x−1)(x+4).
2x2+7x−42x^2 + 7x - 42x2+7x−4
2x2−7x−42x^2 - 7x - 42x2−7x−4
2x2+7x+42x^2 + 7x + 42x2+7x+4
2x2−42x^2 - 42x2−4