问题
解答题
已知(x2+px+8)与(x2﹣3x+q)的乘积中不含x3和x2项,求p、q的值.
答案
解:∵(x2+px+8)(x2﹣3x+q)
=x4﹣3x3+qx2+px3﹣3px2+pqx+8x2﹣24x+8q
=x4+(p﹣3)x3+(q﹣3p+8)x2+(pq﹣24)x+8q.
∵乘积中不含x2与x3项,
∴p﹣3=0,q﹣3p+8=0,
∴p=3,q=1.
已知(x2+px+8)与(x2﹣3x+q)的乘积中不含x3和x2项,求p、q的值.
解:∵(x2+px+8)(x2﹣3x+q)
=x4﹣3x3+qx2+px3﹣3px2+pqx+8x2﹣24x+8q
=x4+(p﹣3)x3+(q﹣3p+8)x2+(pq﹣24)x+8q.
∵乘积中不含x2与x3项,
∴p﹣3=0,q﹣3p+8=0,
∴p=3,q=1.