1) If A is an n X n diagonalizable matrix with a single eigenvalue A, then A = AI\". 2) If A and B are diagonalizable n X n matrices, then A + B is also diagonalizable. 3) If the columns of an n x 71 matrix are orthonormal, then its rows are as well. 4) If A and B are similar n X n matrices, then they have the same rank. 5) Suppose v1, v2, v3 are vectors in R\" with v1 orthogonal to v2. Then v1, v2, v3 form an orthogonal set if and only if the projection of v3 to the span of V1,V2 is the zero vector