Solution
= Solution
The weighted sum is $(2\ell+2)(\ell/2)+(2\ell)(-(\ell+1)/2)=0$, times $\lambda\hbar^2$, so the centre of gravity is unchanged.
= Solution
The weighted sum is $(2\ell+2)(\ell/2)+(2\ell)(-(\ell+1)/2)=0$, times $\lambda\hbar^2$, so the centre of gravity is unchanged.