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Find the inverse of the following matrix by the adjoint method. [2-243] - Mathematics and Statistics

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प्रश्न

Find the inverse of the following matrix by the adjoint method.

`[(2,-2),(4,3)]`

योग

उत्तर

Let A = `[[2,-2],[4,3]]`

|A|= `|[2,-2],[4,3]|` = 6 + 8 = 14 `≠` 0

∴  A−1 exist

First we have to find the co-factor matrix

= [Aij]2×2′, where Aij = (−1)i+jMij

Now, A11 = (− 1)1+1M11 = 3

A12 = (− 1)1+2M12 = − 4

A21 = (− 1)2+1M21 = (− 2) = 2

A22 = (− 1)2+2M22 = 2

Hence, the co-factor matrix

 = `[("A"_11,"A"_12),("A"_21,"A"_22)]` = `[(3,-4),(2,2)]`

∴ adj A `=[(3,2),(-4,2)]`

∴ A−1 = `1/|"A"|` (adj A) = `1/14[(3,2),(-4,2)]`

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