[See Steps] (a) Two n x n matrices A and B are said to be similar if there exists a nonsingular matrix C such that B=C^-1 A C Prove that if A and B are
Question: (a) Two n x n matrices \(\mathrm{A}\) and \(\mathrm{B}\) are said to be similar if there exists a nonsingular matrix C such that
\[B=C^{-1} A C\]Prove that if \(\mathrm{A}\) and \(\mathrm{B}\) are similar matrices, they have the same eigenvalues.
Hint: If \(\lambda\) is an eigenvalue of \(B\) then, by definition,
\[\left|B-\lambda I_{n}\right|=0\](b) Prove that if A is an idempotent matrix, the eigenvalues of A are either 0 or 1 .
(c) Let
\[M=I_{n}-X\left(X^{\prime} X\right)^{-1} X^{\prime}\]where \(X\) is an n x k matrix of rank \(\mathrm{k}\). Prove that
\[\operatorname{tr}(M)=n-k\]Hint: Use the properties of the trace operator stated in lectures.
Deliverable: Word Document 