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Question
Given A = `[(2, 4, 0),(3, 9, 6)]` and B = `[(1, 4),(2, 8),(1, 3)]` is (AB)′ = B′A′?
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Solution
Here, A = `[(2, 4, 0),(3, 9, 6)]`, B = `[(1, 4),(2, 8),(1, 3)]`
AB = `[(2, 4, 0),(3, 9, 6)] [(1, 4),(2, 8),(1, 3)]`
= `[(2 + 8 + 0, 8 + 32 + 0),(3 + 18 + 6, 12 + 72 + 18)]`
= `[(10, 40),(27, 102)]`
L.H.S. (AB)' = `[(10, 27),(40, 102)]`
Now B = `[(1, 4),(2, 8),(1, 3)]`
⇒ B' = `[(1, 2, 1),(4, 8, 3)]`
A = `[(2, 4, 0),(3, 9, 6)]`
⇒ A' = `[(2, 3),(4, 90),(0, 6)]`
R.H.S. B'A' = `[(1, 2, 1),(4, 8, 3)][(2, 3),(4, 9),(0, 6)]`
= `[(2 + 8 + 0, 3 + 18 + 6),(8 + 32 + 0, 12 72 + 18)]`
=`[(10, 27),(40, 102)]`
= L.H.S.
Hence, L.H.S. = R.H.S.
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