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Question
Choose the correct answer from the given four options :
If B = `[(1, 5),(0, 3)]` and A – 2B = `[(0, 4),(-7, 5)]` then the matrix A is equal to
Options
`[(2, 14),(-7, 11)]`
`[(-2, 14),(7, 11)]`
`[(2, -14),(7, 11)]`
`[(-2, 14),(-7, 11)]`
Solution
B = `[(1, 5),(0, 3)]`
and
A – 2B = `[(0, 4),(-7, 5)]`
2B = 2 x `[(-1 , 5),(0, 3)] = [(-2, 10),(0, 6)]`
A – 2B = `[(0, 4),(-7, 5)]`
⇒ A = `[(0, 4),(-7, 5)] + 2"B"`
⇒ A = `[(0, 4),(-7, 5)] + [(2, 10),(0, 6)]`
= `[(0 - 2, 4 + 10),(-7 + 0, 5 + 6)]`
= `[(-2, 14),(-7, 11)]`.
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