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Find the inverse of A = [123115247] by using elementary row transformations. - Mathematics and Statistics

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प्रश्न

Find the inverse of `[(1,2,3),(1,1,5),(2,4,7)]` by using elementary row transformations.

बेरीज

उत्तर

Let A = `[(1,2,3),(1,1,5),(2,4,7)]` 

|A| = `|(1,2,3),(1,1,5),(2,4,7)|`

= 1(7 - 20) - 2(7 - 10) + 3(4 - 2)

= - 13 + 6 + 6 

= - 1 ≠ 0

∴ A-1 exists.

Consider AA-1 = I

∴ `[(1,2,3),(1,1,5),(2,4,7)] "A"^-1= [(1,0,0),(0,1,0),(0,0,1)]`

By `"R"_2 - "R"_1  "and"  "R"_3 - 2"R"_1` , we get,

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

By `(- 1)"R"_2`we get

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

By `"R"_1 - 2"R"_2`we get

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

By `"R"_1 - 7"R"_3` and  `"R"_2 + 2"R"_3` we get

`[(1,0,0),(0,1,0),(0,0,1)] "A"^-1 = [(13,2,-7),(-3,-1,2),(-2,0,1)]`

∴ A-1 = `[(13,2,-7),(-3,-1,2),(-2,0,1)]`

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Elementry Transformations
  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 2: Matrics - Miscellaneous exercise 2 (A) [पृष्ठ ५४]

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