Here's the graph:
The equation of any circle is
(x - h)2 + (y - k)2 = r2
The center is (h,k) and you are given that.
Look at the graph and count the units between the center
and where the circle touches the y-axis. That's the radius r.
Now substitute values for h,k, and r into
(x - h)2 + (y - k)2 = r2
[By the way, don't substitute anything for x and y, just
leave them as x any y]
If you have trouble, tell me in the thank-you note form below,
and I'll get back to you by email.
Edwin