设 x^4-5x^3+11x^2+mx+n=(x^2-2x+1)(x^2+px+q)则：x^4-5x^3+11x^2+mx+n=x^4+(p-2)x^3+(q-2p+1)x^2+(p-2q)x+q比较系数得到：p-2=-5q-2p+1=11解得：p=-3，q=4所以，m=p-2q=-11，n=q=4
