phamwuwu phamwuwu 15-12-2021 Mathematics contestada : Cho A = 2 1 0 2 3 −4 ! , B = 1 0 −3 −2 1 4 0 −2 7 , C = −1 −2 0 9 2 0 . Tính a) −2A + 3C T . b) AB.