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Question
If X = `[(3, 1, -1),(5, -2, -3)]` and Y = `[(2, 1, -1),(7, 2, 4)]`, find 2X – 3Y
Solution
Given that X = `[(3, 1, -1),(5, -2, -3)]` and Y = `[(2, 1, -1),(7, 2, 4)]`
2X – 3Y = `2[(3, 1, -1),(5, -2, -3)] - 3[(2, 1, -1),(7, 2, 4)]`
= `[(2 xx 3, 2 xx 1, -2 xx 1),(2 xx 5, -2 xx 2, -2 xx 3)] - [(3 xx 2, 1 xx 3, -1 xx 3),(3 xx7, 3 xx 2, 3 xx 4)]`
= `[(6, 2, -2),(10, -4, -6)] - [(6, 3, -3),(21, 6, 12)]`
= `[(6 - 6, 2 - 3, -2 + 3),(10 - 21, -4 - 6, -6 - 12)]`
= `[(0, -1, 1),(-11, -10, -18)]`
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