Hi im having trouble with this problem.

Find an equation of the largest sphere with the given center that is contained in the first octant. (6, 4, 9)

So I thought that the radius would be distance from the center to the origin.

I get 36+16+81=133 for my r squared

so i submitted this equation and don't have it right. i feel like its something simple im missing

$\displaystyle (x-6)^2+(y-4)^2+(z-9)^2=133$