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Express the following matrices as the sum of a symmetric and a skew symmetric matrix: [6-22-23-12-13] - Mathematics

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Question

Express the following matrices as the sum of a symmetric and a skew symmetric matrix:

`[(6, -2,2),(-2,3,-1),(2,-1,3)]`

Sum
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Solution

A = `[(6,-2,2),(-2,3,-1),(2,-1,3)]`

`=> "A'"  = [(6,-2,2),(-2,3,-1),(2,-1,3)]`

`therefore "A" + "A'" = [(6,-2,2),(-2,3,-1),(2,-1,3)] + [(6,-2,2),(-2,3,-1),(2,-1,3)]`

`= [(6 + 6, -2 - 2, 2 + 2),(-1 -1, 3 + 3, -1 - 1),(2 + 2, -1 -1, 3 + 3)]`

`= [(12,-4,4),(-4,6,-2),(4,-2,6)]`

`therefore 1/2 ("A" + "A'") = 1/2 [(12,-4,4),(-4,6,-2),(4,-2,6)]`

= `[(6,-2,2),(-2,3,-1),(4,-1,3)]` = is a symmetric matrix.

`therefore "and" ("A" - "A'") = [(6,-2,2),(-2,3,-1),(4,-1,3)]- [(6,-2,2),(-2,3,-1),(4,-1,3)]`

`= [(0,0,0),(0,0,0),(0,0,0)]`

`therefore 1/2 ("A" - "A'") + 1/2 [(0,0,0),(0,0,0),(0,0,0)] = 0`

Hence, A `= 1/2 ("A" + "A'") + 1/2 ("A" - "A'")`

`= [(6,-2,2),(-2,3,-1),(2,-1,3)] + [(0,0,0),(0,0,0),(0,0,0)]`

`= [(6,-2,2),(-2,3,-1),(2,-1,3)] = "A"`

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Chapter 3: Matrices - Exercise 3.3 [Page 89]

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NCERT Mathematics Part 1 and 2 [English] Class 12
Chapter 3 Matrices
Exercise 3.3 | Q 10.2 | Page 89

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