13. (a) Is {(-3,0,4),(0,-1,2),(1,1,3)} a linearly independent set for R^3? (b) Let B = {(3,9),(-4, a)), find all values of a so that B becomes a basis for R^2? (c) Let B = {(2,-4),(3,8)} be a basis for Rº. Find the coordinate vector of (1,1) relative to the basis B for R^2