1 Given matrix A = [23] 2 Determine if matrices A= [23] and B= find A+B and AB. and B= [] commute 1 2 3 3 Calculate the determinant of A = [5 7 4] using the expansion method. 8 10 4 Prove that if a matrix D is invertible, then det(D)#0. 5 Show that the set of all 2x2 symmetric matrices forms a vector space.