(3x-4)(x-6)-(x-6)-(x-6)(2x+7)-3x(x-6)
=(x-6)(3x-4-1-2x-7-3x)
=(x-6)(-2x-12)
=-2(x-6)(x+6)
ou
(3x-4)(x-6)-(x-6)-(x-6)(2x+7)-3x(x-6)
=3x²-18x-4x+24-x+6-(2x²+7x-12x-42)-(3x²-18x)
=3x²-18x-4x+24-x+6-2x²-7x+12x+42-3x²+18x
=-2x²+72
=-2(x²-36) [a²-b²=(a-b)(a+b)]
=-2(x-6)(x+6)
