Vector in space (find equation for a sphere)

Find the equation of the sphere with largest radius centered at (1; 2; 3) that is contained in
the first octant of R^3. (R^3 probably mean in 3D)

The min distance to axis planes is min(1,2,3) = 1. Therefore the sphere equation is

(x-1)^2 + (y-2)^2 + (z-3)^2 = 1