2. Fix any positive integer n and consider the trace operator: Tr : Rnx - R. The trace operator sums up the diagonal entries of a matrix. In other words, if A E Rnxn and the entry in the ith row and jth column is aij, then Tr(A) = _ _jan. Note that the trace operator is a linear operator. Define the inner product on Rnxn as (A, B) = Ci-1 2_1 dijbij. (Here, similarly to above, bij refers to the entry in the ith row and jth column.) Define the inner product on R as simply (x, y) = xy. What is the adjoint of Tr(.)