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If `A=[1 1-1 2 0 3 3-1 2]`, `B=[1 0-13 2 4]`and `C=[1 2 3-4 2 0-2 1]`, find A(BC), (AB)C and show that `(A B)C = A(B C)`. |
Answer» Here, `BC = [[1+6,2+0,3-6,-4+3],[0+4,0+0,0-4,0+2],[-1+8,-2+0,-3-8,4+4]]` `= [[7,2,-3,-1],[4,0,-4,2],[7,-2,-11,8]]` Now, `A(BC) = [[1,1,-1],[2,0,3],[3,-1,2]][[7,2,-3,-1],[4,0,-4,2],[7,-2,-11,8]]` `A(BC) = [[7+4-7,2+0+2,-3-4+11,-1+2-8],[14+0+21,4+0-6,-6+0-33,-2+0+24],[21-4+14,6-0-4,-9+4-22,-3-2+16]]` `=[[4,4,4,-7],[35,-2,-39,22],[31,2,-27,11]]` Now, `AB = [[1,1,-1],[2,0,3],[3,-1,2]] [[1,3],[0,2],[-1,4]]` `=[[1+0+1,3+2-4],[2+0-3,6+0+12],[3+0-2,9-2+8]]` `=[[2,1],[-1,18],[1,15]]` `(AB)C = [[2,1],[-1,18],[1,15]][[1,2,3,-4],[2,0,-2,1]]` `=[[2+2,4+0,6-2,-8+1],[-1+36,-2+0,-3-36,4+18],[1+30,2+0,3-30,-4+15]]` `=[[4,4,4,-7],[35,-2,-39,22],[31,2,-27,11]]` `:. A(BC) = (AB)C. ` |
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