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2[mn+(-3m)]-3(2n-mn),其中m+n=2,mn=-3 求值
人气:185 ℃ 时间:2020-05-09 13:53:49
解答
2[mn+(-3m)]-3(2n-mn)
=2mn-6m-6n+3mn
=5mn-6(m+n)
=5×(-3)-6×2
=-27
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