Question

(x的三次方+px+q)(x的二次方-3x+2)不含x的三次方和x的二次方项求p,q

Answer 1

原题是:(x^3+px+q)(x^2-3x+2)展开式不含x^3和x^2项.求p,q

(x^3+px+q)(x^2-3x+2)

=x^5-3x^4+(p+2)x^3-(3p-q)x^2+(2p-3q)x+2q

由已知得 p+2=0 且 3p-q=0

解得 p=-2 q=-6

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