x²+y²+4x-y+4分之17=0,
x²+y²+4x-y+4分之17
=(x+2)²+(y-1/2)²=0
x+2=0
y-1-2=0
x=-2
y=1/2
2x-3y=-4-3/2=-11/2
x²+y²+4x-y+17/4=0
=>(x²+4x+4)+(y²-y+1/4)=0
=>(x+2)^2+(y-1/2)^2=0
=>x=-2, y=1/2
所以2x-3y = -11/2
解:
∵x²+y²+4x-y+17/4=0
∴x²+4x+4+y²-y+1/4=0
∴(x+2)²+(y-1/2)=0
∴x=-2,y=1/2
∴2x-3y=-4-3/2=-11/2