Which of these subsets of P3 are linearly dependent and which are independent?
(a) {3 - x + 9x2, 5 - 6x + 3x2, 1 + 1x - 5x2}
(b) {-x2, 1 + 4x2}
(c) {2 + x + 7x2, 3 - x + 2x2, 4 - 3x2}
(d) {8 + 3x + 3x2, x + 2x2, 2 + 2x + 2x2, 8 - 2x + 5x2}