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महाराष्ट्र राज्य शिक्षण मंडळएचएससी विज्ञान (सामान्य) इयत्ता १२ वी

Find the inverse of the following matrix (if they exist): [3-102-7] - Mathematics and Statistics

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प्रश्न

Find the inverse of the following matrix (if they exist):

`[(3,-10),(2,-7)]`

बेरीज

उत्तर

Let A = `[(3,-10),(2,-7)]`

∴ |A| = `|(3,-10),(2,-7)| = - 21 + 20 = - 1 ne 0`

∴ A-1 exists.

Consider AA-1 = I

∴ `[(3,-10),(2,-7)] "A"^-1 = [(1,0),(0,1)]`

By R1 - R2, we get,

∴ `[(1,-3),(2,-7)] "A"^-1 = [(1,-1),(0,1)]`

By R2 - 2R1, we get,

`[(1,-3),(0,-1)] "A"^-1 = [(1,-1),(-2,3)]`

By (- 1)R2, we get,

`[(1,-3),(0,1)] "A"^-1 = [(1,-1),(2,-3)]`

By R1 + 3R2, we get,

`[(1,0),(0,1)] "A"^-1 = [(7,-10),(2,-3)]`

∴ `"A"^-1 = [(7,-10),(2,-3)]`

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