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(x-1)²+ │y+1│=0 求2x²y-(2x²y-4x²y+5xy²)的值
RT
人气:424 ℃ 时间:2020-10-02 07:44:54
解答
因为(x-1)≥0│y+1│≥0
(x-1)²+ │y+1│=0
所以x=1,y=-1
2x²y-(2x²y-4x²y+5xy²)=4x2y-5xy2
=xy(4x-5y)
=-1*9
=-9
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