3. this question is all about the trace of a matrix, denoted tr(a). recall that the trace of a matrix is the sum of its diagonal entries. 21 and b=1-1 i (a) let a : : : |-2 ·1 and (b) prove that for any n x n matrices a and b, tr(ab)- tr(ba). (c) prove that if a is an n × n matrix and p is an invertible n×n matrix, then tr (pap-1) = . compute tr(ab) and tr(ba) tr(a).