(13: a) [4+4- marks] Let W = span{(l,1, 1], (2,3,1), (5,6, 2)}. i. Find a basis for W. ii. Determine whether the vector X = (2,5,7) belongs to W. b) [6 marks] Let A be an m X 11: matrix. Show that the solution set of a homogeneous linear system AX = O in n unknowns is a subspace of R." c) [6 marks| Find a 2 x 2 matrix A whose eigenvalues are .1, = 1 and 212 = 2, and associated eigenvectors are X1 = [a] and X2 = E], respectively