I was asked to simplify the following expression:
and my simplification went as follows..
But my book gives an answer of
Where did I go wrong?
The implied summation is over all three indices, since they're all repeated. The Levi-Civita symbol's relation to the Kronecker delta is given by
where the summation is explicitly indicated. Applying this to your situation yields
I think your mistake was in evaluating
That's equal to 3, not 9.