Properties of transpose

Let A be a real n×n matrix and let A denote its transpose.

  1. Prove that (Av)w=v(Aw) for all vectors v,wRn. Hint: Recall that the dot product uv equals the matrix product uv.
  2. Suppose now A is also symmetric, i.e., that A=A. Also suppose v and w are eigenvectors of A with different eigenvalues. Prove that v and w are orthogonal.