已知x,y满足x²+y²+5/4=x-2y,则2x+y的值为多少?
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已知x,y满足x²+y²+5/4=x-2y,则2x+y的值为多少?
已知x,y满足x²+y²+5/4=x-2y,则2x+y的值为多少?
已知x,y满足x²+y²+5/4=x-2y,则2x+y的值为多少?
x²+y²+5/4=x-2y
x²-x+y²+2y+5/4=0
(x²-x+1/4)+(y²+2y+1)=0
(x-1/2)²+(y+1)²=0
∴x-1/2=0,y+1=0
∴x=1/2,y=-1
∴2x+y
=2*1/2+(-1)
=1-1
=0
解x²+y²+5/4=x-2y可以转化为
(x-1/2)^2+(y+1)^2-1/4-1+5/4=0
(x-1/2)^2+(y+1)^2=0
所以x-1/2=0,y+1=0
所以x=1/2,y=-1
所以2x+y=0