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Question
If A = `[(1, -2),(5, 6)], "B" = [(3, -1),(3, 7)]`, Find AB - 2I, where I is unit matrix of order 2.
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Solution
AB = `[(1, -2),(5, 6)] [(3, -1),(3, 7)]`
= `[(3 - 6, -1 - 14),(15 + 18, -5 + 42)]`
= `[(-3, -15),(33, 37)]`
∴ AB – 2I = `[(-3, -15),(33, 37)] -2[(1, 0),(0, 1)]`
= `[(-3, -15),(33, 37)] - [(2, 0),(0, 2)]`
= `[(-5, -15),(33, 35)]`
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