先化简,再求值:m(3m-1)-(m+3)(m-3)-2(m-1)平方,其中m=-1⼀2

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2025-03-03 08:44:03
推荐回答(3个)
回答1:

m(3m-1)-(m+3)(m-3)-2(m-1)平方
=3m²-3m-m²+9-2m²+4m-2
=m+7
=-0.5+7
=6.5

回答2:

m(3m-1)-(m+3)(m-3)-2(m-1)^2
=3m^2-m-(m^2-9)-2(m^2-2m+1)
=3m^2-m-m^2+9-2m^2+4m-2
=3m+7
因为m=-1/2
所以原式=5.5

回答3:

m(3m-1)-(m+3)(m-3)-2(m-1)^2
=3m^2-m-(m^2-9)-2(m^2-2m+1)
=3m^2-m-m^2+9-2m^2+4m-2
=3m^2-m^2-2m^2-m+4m-2+9
=3m+7
=3*(-1/2)+7
=-3/2+7
=11/2