Find the center locus equation of two circles x2 + y2 = 4 and X2 + y2-12x-64 = 0

Find the center locus equation of two circles x2 + y2 = 4 and X2 + y2-12x-64 = 0

This is the case of two circumscribed circles
Root sign (x ^ 2 + y ^ 2) = R + 2 (X-6) ^ 2 + y ^ 2 = 100
Root [(X-6) ^ 2 + y ^ 2] = R + 10
Root sign (x ^ 2 + y ^ 2) - 2 = root sign [(X-6) ^ 2 + y ^ 2] - 10
This is the trajectory equation
It seems that there is also the situation of introspection, the landlord refueling calculation