x2+nx+3与 x2－3x+m的积不含x2、X3
问题描述：
x2+nx+3与 x2－3x+m的积不含x2、X3
求m/n的值
答
(x^2+nx+3)(x^2-3x+m)=x^2(x^2-3x+m)+nx(x^2-3x+m)+3(x^2-3x+m)=x^4-3x^3+mx^2+nx^3-3nx^2+mnx+3x^2-9x+3m=x^4+(n-3)x^3+(m-3n+3)x^2+(mn-9)x+3m积不含x^2、x^3n-3=0m-3n+3=0解得：m=6,n=3m/n=6/3=2