The operators $\mathrm{S}_{ \pm}$are defined by $\mathrm{S}_{ \pm}=\mathrm{S}_{\mathrm{x}} \pm \mathrm{iS}_{\mathrm{y}}$ where $\mathrm{S}_{\mathrm{x}}$ and $\mathrm{S}_{\mathrm{y}}$ are components of the spin angular momentum operator. The commutator $\left[\mathrm{S}_{\mathrm{x}}, \mathrm{S}_{+}\right]$is
(a)$\hbar \mathrm{S}_{+}$
(b)$\hbar \mathrm{S}_{-}$
(c)$-\hbar \mathrm{S}_{+}$
(d)$-\hbar \mathrm{S}_{-}$
Answer
SELF-PRACTICE — the source book printed no answer.
Nothing is invented here, so this question has no answer on record.