-2 5 3 -1 B x A = 1 8 2 4 (-2) x 3 + 5 x 2 (-2) x (-1) + 5 x 4 = 1 x 3 + 8 x 2 1 x (-1) + 8 x 4 4 22 = 19 31 19 November 2020 17