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4x^2y-[6xy-2(4xy-2)-x^2y]+1,其中x=-1/2,y=4
五分钟之内~
人气:479 ℃ 时间:2020-09-26 16:37:47
解答
4x^2y-[6xy-2(4xy-2)-x^2y]+1
=4x^2y-6xy+8xy-4+x^2y+1
=5x^2y+2xy-3 把x=-1/2,y=4带入
=5(-1/2)²×4+2(-1/2)×4-3
=5-4-3
=-2
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