Chapter 9 - Polar Coordinates; Vectors - 9.6 Vectors in Space - 9.6 Assess Your Understanding - Page 626: 69

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

If $r$ is the radius and $P_0(x_0,y_0,z_0)$ is the center of the sphere then the standard form of the equation of the sphere is: $(x-x_0)^2+(y-y_0)^2+(z-z_0)^2=r^2.$ Hence, here: $(x-3)^2+(y-1)^2+(z-1)^2=1$