Explain whether or not the following are bases. a) S=1-x²,1-2x basis of P_2? b) S=(-1,0,0),(0,0,1),(1,0,0) basis of R³? c) S=([2,0],[0,3]),([1,4],[0,1]),([0,1],[3,2]),([0,1],[2,0]) basis of ________.