Question 160207
<pre><font size = 4 color = "indigo"><b>
If you'd draw the circle, making it tangent to the y-axis,
and with center (3,-1), you'd easily be able to find the radius,
and then you'd know that C would be the square of the radius.

{{{drawing(200,200,-3,7,-5,5, graph(200,200,-3,7,-5,5),
circle(3,-1,3) )}}}

Now draw in the radius from the center (3,-1) over to the y-axis 
where it's tangent:

{{{drawing(200,200,-3,7,-5,5, graph(200,200,-3,7,-5,5),
circle(3,-1,3), line(3,-1,0,-1) )}}}

You can easily tell that radius is 3 units long, so r=3

So the equation:

{{{(x-h)^2+(y+k)^2=r^2}}}

is

{{{(x-3)^2+(y+1)^2=3^2}}}

{{{(x-3)^2+(y+1)^2=9}}}

So now you know that A=3, B=-1 and C=9.

Edwin</pre>