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## Homework Statement

Show that..

[tex]e^{L}a e^{-L}=a+[L,a]+\frac{1}{2!}[L,[L,a]]+\frac{1}{3!}[L[L[L,a]]]+....[/tex]

Where L and a are operators.

## The Attempt at a Solution

Right now I am writing the exponentials as their Taylor expansions, and then expanding the RHS of the above equation to see if they are equal. I am having difficulties however, because I cannot seem to make them equal!