设xy为正数,且满足x2-2xy-y2=2xy 求x+y分之x-y的值sorry.打错了。设xy为正数,且满足x2-2xy-y2=0 求x+y分之x-y的值

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设xy为正数,且满足x2-2xy-y2=2xy 求x+y分之x-y的值sorry.打错了。设xy为正数,且满足x2-2xy-y2=0 求x+y分之x-y的值
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设xy为正数,且满足x2-2xy-y2=2xy 求x+y分之x-y的值sorry.打错了。设xy为正数,且满足x2-2xy-y2=0 求x+y分之x-y的值
设xy为正数,且满足x2-2xy-y2=2xy 求x+y分之x-y的值
sorry.打错了。
设xy为正数,且满足x2-2xy-y2=0 求x+y分之x-y的值

设xy为正数,且满足x2-2xy-y2=2xy 求x+y分之x-y的值sorry.打错了。设xy为正数,且满足x2-2xy-y2=0 求x+y分之x-y的值
x2-2xy-y2=2xy
x²-y²=4xy
两边同除以y²得:
(x/y)²-4(x/y)-1=0
[(x/y)-2]²=5
x/y=2+√5;x/y=2-√5(<0;舍去)
x+y分之x-y
分子分母同除以y得:
原式=(x/y-1)/(x/y+1)
=(√5+1)/(√5+3)
=(√5+1)(3-√5)/4
=(3-5+2√5)/4
=(√5-1)/2

2x-2xy-2y=2xy化解得x-y=0因为x、y都是正数及x y>0答(x y)÷(x-y)=0

x^2-y^2=2xy,得x/y-y/x=2,即(y/x)^2+2(y/x)-1=0∴y/x=-1+√2或y/x=-1-√2(舍去,因为x,y都是正数)。即(x-y)/(x+y)=√2-1