已知在(x²+ax+3)(2x²-x-2)的乘积中,不含x²项,求-¼a(a²-2a)的值
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已知在(x²+ax+3)(2x²-x-2)的乘积中,不含x²项,求-¼a(a²-2a)的值
已知在(x²+ax+3)(2x²-x-2)的乘积中,不含x²项,求-¼a(a²-2a)的值
已知在(x²+ax+3)(2x²-x-2)的乘积中,不含x²项,求-¼a(a²-2a)的值
(x²+ax+3)(2x²-x-2)
=2x^4+2ax³+6x²-x³-ax²-3x-2x²-2ax-6
=2x^4+(2a-1)x³+(4-a)x²-(2a+3)x-6
因为不含x²项
所以4-a=0
a=4
原式=-1×(16-8)=-8