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## Homework Statement

Show that the expectation value of angular momentum <Lx> is zero

## Homework Equations

L±|l,m⟩ = SQRT(l(l+1)−m(m±1)h|l,m±1⟩

L± = Lx ± iLy

## The Attempt at a Solution

I'm supposed to use ladder operators here to show <Lx> is zero.

I start with <Lx>=<l,m|Lx|l,m> but don't know where to go from here. I've tried different things but all the methods I've tried seem to lead to a dead end...