(x^2+mx+n)×(x^3+2x-1)=x^5+mx^4+nx^3+2x^3+2mx^2+2nx-x^2-mx-n=x^5+mx^4+x^3(n+2)+x^2(2m-1)+2nx-mx-n∵x^2+mx+n与x^3+2x-1的乘积中不含有x^3项和x^2项∴n+2=0 2m-1=0 ∴n=-2 m=1/2
