4(3x^2-x-1)(x^2+2x-3)-(4x^2+x-4)^2=4(3x^2-x-1)(x^2+2x-3)-[(3x^2-x-1)+(x^2+2x-3)]^2=4(3x^2-x-1)(x^2+2x-3)-(3x^2-x-1)^2-2(3x^2-x-1)(x^2+2x-3)-(x^2+2x-3)^2=-(3x^2-x-1)^2+2(3x^2-x-1)(x^2+2x-3)-(x^2+2x-3)^...