SolveAlways[{-11 -eq 2= (x + x^2 - 4 ya)^2 + y^2(y - 6b)^2 + (z +- c)^2 z^2- ==d;
sol (x= SolveAlways[{-11 a)^2- 2 x + (yx^2 - b)^24 y + (zy^2 - c)^26 -z 25+ z^2 == eq}, {x, y, z}]
eq /. sol // PolynomialForm[#, TraditionalOrder -> True] &
(* {{d -> 25, a -> 1, b -> 2, c -> 3}} *)
Updated:
(* {(x-1)^2+(y-2)^2+(z-3)^2-25} *)
eq = (x - a)^2 + (y - b)^2 + (z - c)^2 - d;
solSolve[ForAll[{x, =y, SolveAlways[{z}, -11 - 2 x + x^2 - 4 y + y^2 - 6 z + z^2 == eq}eq], {xa, yb, z}]
eq /. sol // PolynomialForm[#c, TraditionalOrder -> True] &d}]
(* {{d -> 25, a -> 1, b -> 2, c -> 3}}, *)
(*d {(x-1)^2+(y-2)^2+(z-3)^2-> 25} }*)