问题 填空题

若(x2+mx+n)(x2-2x-3)的乘积中不含x3、x2项,则m=______,n=______.

答案

∵(x2+mx+n)(x2-2x-3)

=x4-2x3-3x2+mx3-2mx2-3mx+nx2-2nx-3n,

=x4+(-2+m)x3+(-3-2m+n)x2+(-3m-2n)x-3n,

∴要使(x2+mx+n)(x2-2x-3)的乘积中不含x3与x2项,

则有

-2+m=0
-3-2m+n=0

解得

m=2
n=7

故答案为:2,7.

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