x²-4x+y²+6y+13=0
(x²-4x+4)+(y²+6y+9)=0
(x-2)²+(y+3)²=0
x-2=0 ,y+3=0
x=2 ,y=-3
点P的坐标为(2,-3),把x=2 ,y=-3代入y=k/x可得:
k/2=-3
k=-6