X,Y为正数,且XY-(X+Y)=1,则A.X+Y=2(根号2+1)C.X+Y=(根号2+1)^2理由?
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![X,Y为正数,且XY-(X+Y)=1,则A.X+Y=2(根号2+1)C.X+Y=(根号2+1)^2理由?](/uploads/image/z/4059154-10-4.jpg?t=X%2CY%E4%B8%BA%E6%AD%A3%E6%95%B0%2C%E4%B8%94XY-%EF%BC%88X%2BY%EF%BC%89%3D1%2C%E5%88%99A.X%2BY%3D2%28%E6%A0%B9%E5%8F%B72%2B1%29C.X%2BY%3D%28%E6%A0%B9%E5%8F%B72%2B1%29%5E2%E7%90%86%E7%94%B1%3F)
X,Y为正数,且XY-(X+Y)=1,则A.X+Y=2(根号2+1)C.X+Y=(根号2+1)^2理由?
X,Y为正数,且XY-(X+Y)=1,则
A.X+Y=2(根号2+1)
C.X+Y=(根号2+1)^2
理由?
X,Y为正数,且XY-(X+Y)=1,则A.X+Y=2(根号2+1)C.X+Y=(根号2+1)^2理由?
XY-(X+Y)=1
xy=1+(x+y)0
所以a>2+2根号2
选B
(x-1)(y-1)=2
设a=x-1,b=y-1
则ab=2.x+y=a+b+2》2sqrt(ab)+2=2sqrt(2)+2
sqrt为根号
所以选B
XY-(X+Y)=1
4(x+y)+4=4xy<=(x+y)^2
x+y=t>0
tt-4t-4>=0
(t-2)^2>=8
t>=2+2√2