What are the equations for angular momentum?

AdrianMay
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Hi folks,

The attachment is from Sakurai where he's getting started on angular momentum. I don't understand how he gets between the two equations I stuck a ? on. Any hints gratefully appreciated.

Adrian.
 

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  • sak.GIF
    sak.GIF
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Hi Adrian! :smile:

It's ordinary algebra …

A(pq + rs)B = ApqB + ArsB,

together with Sz|+> = |+>, Sz|-> = -|->, and the expansion definition of exp :wink:
 
I swear the exact same question was on this forum or the HW:Advanced Physics 2 weeks ago.
 

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