已知:x2+mx+n乘以x+2得到积是x3+2x+12,求m,n的值.

问题描述:

已知:x2+mx+n乘以x+2得到积是x3+2x+12,求m,n的值.

根据题意得:(x2+mx+n)(x+2)=x3+(2+m)x2+(2m+n)x+2n=x3+2x+12,
则2+m=0,2n=12,
解得:m=-2,n=6.