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若多项式5x²-2mxy-3y²+4xy-3x+1中不含xy项,求(-m³+2m²-m+1)-(m³+2m²-m
人气:389 ℃ 时间:2019-11-13 17:18:16
解答
5x²-2mxy-3y²+4xy-3x+1
=5x²+(4-2m)xy-3y²-3x+1
不含xy项
所以系数为0
4-2m=0
m=2
(-m³+2m²-m+1)-(m³+2m²-m)
=-m³+2m²-m+1-m³-2m²+m
=-2m³+1
=-2×2³+1
=-15
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