正数x,y满足x2-y2=2xy,求(x-y)/(X+Y)的值

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正数x,y满足x2-y2=2xy,求(x-y)/(X+Y)的值

正数x,y满足x2-y2=2xy,求(x-y)/(X+Y)的值
正数x,y满足x2-y2=2xy,求(x-y)/(X+Y)的值

正数x,y满足x2-y2=2xy,求(x-y)/(X+Y)的值
x2-2xy+Y2-2*y2=0
(X-Y)²-2Y²=0
X=(1-根号2)因为为正数,所以不合题意,舍去
X=(1+根号2)Y
(x-y)/(X+Y)=根号2-1

x^2 - y^2 = 2xy
x/y - y/x = 2
(x/y - y/x)^2 = 4
(x/y + y/x)^2 = 8
x/y+y/x = 2*2^(1/2)
(x-y)/(x+y) = (x-y)^2/(x^2-y^2) = (x^2 - 2xy + y^2)/(2xy)
= (1/2)(x/y +y/x) - 1
=2^(1/2) -1

正数x,y满足x²-y²=2xy,求(x-y)/(X+Y)的值
将方程x²-y²=2xy的两边同除以xy得:(x/y)-(y/x)=2............(1)
令x/y=u,则y/x=1/u,代入(1) 式得u-(1/u)=2,即有u²-2u-1=0,故u=(2+√8)/2=1+√2
于是得(x-y)/(x+y)=[...

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正数x,y满足x²-y²=2xy,求(x-y)/(X+Y)的值
将方程x²-y²=2xy的两边同除以xy得:(x/y)-(y/x)=2............(1)
令x/y=u,则y/x=1/u,代入(1) 式得u-(1/u)=2,即有u²-2u-1=0,故u=(2+√8)/2=1+√2
于是得(x-y)/(x+y)=[(x/y)-1]/[(x/y)+1]=(u-1)/(u+1)=(√2)/(2+√2)=(√2)(2-√2)/2=(2√2-2)/2=√2-1.

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根号2-1