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(3x-y)²-2x(4x-5y)-(x+2y)²
先化简再求值(3x-y)²-2x(4x-5y)-(x+2y)²其中x=2000,y=-2
人气:497 ℃ 时间:2019-09-09 11:47:29
解答
(3x-y)²-2x(4x-5y)-(x+2y)²
=9x²-6xy+y²-8x²+10xy-x²-4xy-4y²
=-3y²
x=2000,y=-2
则原式=-3×(-2)²
=-3×4
=-12
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