7. Determine the coordinates of the centres of the spheres with radius $\sqrt{6}$ tangent to the plane $\pi$ with equation: $$x + 2 y - z + 1 = 0$$ at its point $P$ with coordinates $(1,0,2)$.
7. Determine the coordinates of the centres of the spheres with radius $\sqrt{6}$ tangent to the plane $\pi$ with equation:
$$x + 2 y - z + 1 = 0$$
at its point $P$ with coordinates $(1,0,2)$.