8. Circle C has its center on the line $2 x - y - 7 = 0$ and intersects the y-axis at two points $A ( 0 , - 4 )$ and $B ( 0 , - 2 )$. The equation of circle C is $\_\_\_\_$.
8. Circle C has its center on the line $2 x - y - 7 = 0$ and intersects the y-axis at two points $A ( 0 , - 4 )$ and $B ( 0 , - 2 )$. The equation of circle C is $\_\_\_\_$.\\