18. Given x = [4 1 6] and y = [6 2 7], compute the following arrays a. aij = xiyj b. bij = xi/yj c. ci = xiyi, then add up the elements of c. d. dij = xi/(2 + xi + yj) e. eij = reciprocal of the lesser of xi and yj

19. Find the eigenvalues and associated eigenvectors of the matrix A=[-2 2; 0 -1]

20. Check whether the vectors a = {3; 4; 5}, b = {-3; 0; 5}, c = {4; 4; 4}, d = {3; 4; 0} are linearly independent.