已知x²+y²-2x+8y+17=0,求2x²-3y的值,
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已知x²+y²-2x+8y+17=0,求2x²-3y的值,
已知x²+y²-2x+8y+17=0,求2x²-3y的值,
已知x²+y²-2x+8y+17=0,求2x²-3y的值,
x²+y²-2x+8y+17=0
x²-2x+1+y²+8y+16=0
(X-1)²+(y+4)²=0
所以X-1=0,Y+4=0
X=1,Y=-4
2X²-3Y=2×1²-3×(-4)=2+12=14
即(x²-2x+1)+(y²+8y+16)=0
(x-1)²+(y+4)²=0
所以x-1=0,y+4=0
x=1,y=-4
所以原式=2*1-3*(-4)=14