2. Practice with Einstein summation convention. 3 (a) (10 points) Let M = 5 6 Compute Mi. Note the repeated upper and lower 0 2 4 index means that there is a summation implied! The quantity Mi is called the trace of the matrix M. (b) (15 points) Compute o, the trace of the n x n identity matrix, and write your answer in terms of n. (c) (15 points) The Kronecker delta can be used to compute traces. Show that for any matrix M;, 6; M; = Mj