(3х+1)(4х-2)-6(2х-1)^2+14= (3x+1)(4x-2)-6(2x-1)(2x-1)+14 = (12x2-6x+4x-2)-6(2x-1)(2x-1)+14 = 1(12x2-6x+4x-2)+(-24x2+12x+12x-6)+14 = 12x2-6x+4x-2+(-24x2+12x+12x-6)+14 = 12x2-6x+4x-2-24x2+12x+12x-6+14 = – 12x2 + 22x + 6