# linear algebra

posted by
**mathstudent**
.

Prove that the trace is a similarity invariant.

In other words, if two matrices are similar, then they must have the same trace.

Got the answer from Wikipedia:

tr(AB) = tr(BA)

tr(ABC) = tr(CAB)

tr(P^-1 * A * P) = tr(P^-1 * P * A) = tr(A)