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Math Help - Did I get the right answer? [matrix symmetry]

  1. #1
    Junior Member Hasan1's Avatar
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    Did I get the right answer? [matrix symmetry]

    Find all values of a, b, and c for which A is symmetric.


    I set this matrix equal to its transpose and used them both to make the following system of equations, and solved it by gaussian elimination

    a - 2b + 2c = 3
    2a + b + c = 0
    a + c = -2

    I got a = -18, b = 5, c = 31

    How can I check if this is the right answer?
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  2. #2
    Master Of Puppets
    pickslides's Avatar
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    Quote Originally Posted by Hasan1 View Post

    I got a = -18, b = 5, c = 31

    How can I check if this is the right answer?
    Substitute these values back into A. If A is then symmetric the solution set is correct.
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  3. #3
    Junior Member Hasan1's Avatar
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    What if it is the case that the solution set is correct but there are no such values a,b,c that will make A symmetric?
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  4. #4
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    Quote Originally Posted by Hasan1 View Post
    What if it is the case that the solution set is correct but there are no such values a,b,c that will make A symmetric?
    What? You are asking "what if these numbers make A symmetric but there are no numbers that make A symmetric?" !!!! That's impossible.

    In any case, these numbers are NOT correct because
    -18- 2(5)+ 3(31)= -18- 10+ 93= -28+ 93= 55, not 3
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