- #1
whatisreality
- 290
- 1
Homework Statement
Evaluate
∑##_{j=1}^{n} \delta_{ij} \delta_{jk}## where 1≤i≤n and 1≤k≤n and
##\delta_{ij}## and ##\delta_{jk}## = 1 if i=j
0 otherwise
Homework Equations
The Attempt at a Solution
I'm pretty unsure how to do this. I assume k and i are constant. If that's the case, wouldn't this sum always be zero unless k and i are equal? And 1 if they are equal? So does that mean there are two answers, depending on something that hasn't been specified (i.e. whether i and k are equal)?