- #1
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I'm trying to show that [tex]N=a^\dagger a[/tex] and [tex]K_r=\frac{a^\dagger^r a^r}{r!}[/tex] commute. So basically I need to show [tex][a^\dagger^r a^r,a^\dagger a]=0[/tex]. I'm not quite sure what to do, I've tried using [tex][a,a^\dagger][/tex] in a few places but so far haven't had much success.