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已知xy+yy=3,xx+xy=-1/2,求2xx+3xy+yy的值
人气:227 ℃ 时间:2020-03-21 15:48:52
解答
2xx+3xy+yy
=2xx+2xy+xy+yy
=2(xx+xy)+xy+yy
=2*(-1/2)+3
=3-1
=2
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