The equation of a diameter of circle x2+y2−6x+2y=0 passing through origin is
Comparing with standard eqn of circle x2+y2+2gx+2fy+c=0,
g=−3
f=1
So, the centre M of the circle is at(−g,−f)i.e.(3,−1)
Also it has been stated that the circle passes through the originO(0,0)
So the diameter is OM straight line.
The equation of diameter is (y−0)(x−0)=(3–0)(−1–0)
y+3x=0