已知：X-Y\X+Y=4,求X-Y\2（X+Y)- - 知识问答

已知：X-Y\X+Y=4,求X-Y\2（X+Y)-4X+4Y\X-Y的值

1个回答

(x-y)/(x+y)=4
所以(x+y)/(x-y)=1/4
(x-y)/[2(x+y)]-(4x+4y)/(x-y)
=(1/2)*[(x-y)/(x+y)]-4[(x+y)/(x-y)]
=(1/2)*4-4*(1/4)
=1

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