A circle has an equation of a form,
[tex](x-a)^2+(y-b)^2=r^2[/tex]
Where [tex](a, b)[/tex] is the center and [tex]r[/tex] is the radius.
The coordinates of your circle center are [tex](a,b)=(-9,9)[/tex] and the radius is [tex]r=\sqrt{98}[/tex], so plug that in,
[tex](x-(-9))^2+(y-9)^2=\sqrt{98}^2[/tex]
and simplify to get the equation,
[tex](x+9)^2+(y-9)^2=98[/tex]
Hope this helps :)
