The general equation of a circle is the following
[tex](x-h)^2+(y-k)^2=r^2[/tex]where the point (h,k) is the center of the circle and r is the radius. In our case we have h=-10,k=7 and r=2. So we get
[tex](x-(-10))^2+(y-7)^2=2^2=4[/tex]which is equivalent to
[tex](x+10)^2+(y-7)^2=4[/tex]