x^4+x^3+4x^2+3x+3=(x^4+x³+x²﹚+(3x²+3x+3)=x²﹙x²+x+1)+3(x²+x+1)=(x²+3)(x²+x+1)ax^2-bx^2+bx-ax+a-b=x²(a-b)-x(a-b)+(a-b)=(a-b)(x²-x+1)