(i)[56−17][2314]
=[5(2)−1(3)6(2)+7(3)5(1)−1(4)6(1)+7(4)]
=[10−312+215−46+28]=[733134]
[2314][2314]
=[2(5)+1(6)3(5)+4(6)2(−1)+1(7)3(−1)+4(7)]
=[10+615+24−2+7−3+28]
=[[1639525]
∴ [56−17][2314]≠[2314][56−17]
(ii)101211300−1021−13014
=1(−1)+2(0)+3(2)0(−1)+1(0)+0(2)1(−1)+1(0)+0(2)1(1)+2(−1)+3(3)0(1)+1(−1)+0(3)1(1)+1(−1)+0(3)1(0)+2(−1)+3(4)0(0)+1(1)+0(4)1(0)+1(1)+0(4)
=50−18−101411
−1021−13014101211300
=−1(1)1(0)+0(1)0(1)+(−1(0)+1(1)2(1)+3(0)+4(1)−1(2)+1(1)+0(1)0(2)+(−1)(1)+1(1)2(2)+3(1)+4(1)−1(3)+1(0)+0(0)0(3)+(−1)(0)+1(0)2(3)+3(0)+4(0)
=−116−1011−306
∴ 101211300−1021−13014≠ −1021−13014101211300