x^4+2x^3+5x^2+4x-12=x^4-x³+3x³-3x²+8x²-8x+12x-12=x³(x-1)+3x²(x-1)+8x(x-1)+12(x-1)=(x-1)(x³+3x²+8x+12)=(x-1)(x³+2x²+x²+2x+6x+12)=(x-1)[x²(x+2...