Solution
= Solution
The two free indices are the row and column indices of a <matrix>. The <Kronecker delta> has value one on its diagonal and zero off it, so the answer is \b[the $3\times3$ <identity matrix> $I$].
= Solution
The two free indices are the row and column indices of a <matrix>. The <Kronecker delta> has value one on its diagonal and zero off it, so the answer is \b[the $3\times3$ <identity matrix> $I$].