求代数式2x^2y+{2xy-[3x^2y-2(-3x^2y+2xy)]-4xy^2},其中x=-1/2 y=2

liuzhu7772022-10-04 11:39:543条回答

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shumimi 共回答了17个问题 | 采纳率94.1%: 2x^2y+{2xy-[3x^2y-2(-3x^2y+2xy)]-4xy^2}
=2x^2y+{2xy-[3x^2y+6x^2y-4xy]-4xy^2}
=2x^2y+{2xy-3x^2y-6x^2y+4xy-4xy^2}
=2x^2y+2xy-3x^2y-6x^2y+4xy-4xy^2
=-7x^2y+6xy-4xy^2
=xy(-7x+6-4y)
=(-1/2)*2*[-7*(-1/2)+6-4*2]
=-(7/2+6-8)
=-(7/2-2)
=-3/2; 1年前

xwy849 共回答了5510个问题 | 采纳率: 2x^2y+{2xy-[3x^2y-2(-3x^2y+2xy)]-4xy^2}，
=2x²y+2xy-3x²y-6x²y+4xy-4xy²
=-7x²y+6xy-4xy²

把x=-1/2 y=2代入得
原式=-7/2-6+8
=-3/2; 1年前

blackviva 共回答了1个问题 | 采纳率: GT210跟9500相比谁好点; 1年前

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