I have a small question and I hope I make this clear.
Would one distribute the Kronecker Delta as follows?
$\sum_{j}^n\ ( C + x_j ) \delta_{ij}$
$= \sum_{j}^n\ ( C\delta_{ij} + x_j\delta_{ij} ) $
$= C + \sum_{j}^n\ x_j\delta_{ij} ) $
I believe the answer to be only : $ \ \ x_i $
But I can not reason why the C term should vanish. Any help is appreciated.