3. A symmetric matrix S = S'has orthonormal eigenvectors v1, ..., Un. Then any vector r can be written as a combination r = civi + ... + Cnn. Explain these two formulas: er=cit.ten rSx = Micit .. + Anen. 4. Problem 3 gives a neat form for the Rayleigh quotient: R(x) = = Why is the maximum value of that ratio equal to the largest eigenvalue Al