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Question
Answer the following question:
If A = `[(1, -1, 0),(2, 3, 4),(0, 1, 2)]`, B = `[(2, 2, -4),(-4, 2, -4),(2, -1, 5)]`, show that BA = 6I
Solution
BA = `[(2, 2, -4),(-4, 2, -4),(2, -1, 5)] [(1, -1, 0),(2, 3, 4),(0, 1, 2)]`
= `[(2 + 4 - 0, -2 + 6 - 4, 0 + 8 - 8),(-4 + 4 + 0, 4 + 6 - 4, 0 + 8 - 8),(2 - 2 + 0, -2 - 3 + 5, 0 - 4 + 10)]`
= `[(6, 0, 0),(0, 6, 0),(0, 0, 6)]`
= `6[(1, 0, 0),(0, 1, 0),(0, 0, 1)]`
∴ BA = 6I
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