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anonymous

  • 5 years ago

Can anyone prove y this identity wouldn't work for matrices

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  1. anonymous
    • 5 years ago
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    (a+b)(a+b)=a^2+2ab+b^2

  2. JamesJ
    • 5 years ago
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    This identity is true if and only if AB = BA. So you need just one example of a pair of matrices A and B where that is not the case.

  3. anonymous
    • 5 years ago
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    Ok great thanks :D

  4. anonymous
    • 5 years ago
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    problem is with the commutative law \[(a+b)(a+b)=a^2+ab+ba+b^2\]and .. . what jamesj said

  5. anonymous
    • 5 years ago
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    ok Good but I think I need to use an arguement

  6. anonymous
    • 5 years ago
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    I have to show by example and arguement

  7. anonymous
    • 5 years ago
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    Do i shld just say abt commutative law ok?

  8. anonymous
    • 5 years ago
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    a counter example is all you need. it is almost never the case that AB =BA

  9. anonymous
    • 5 years ago
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    Alrighty Thanks :D

  10. JamesJ
    • 5 years ago
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    Write down a pair of 2x2 matrices and see if commute. [ If you know anything about linear transformations, here are two that don't commute and you can see it geometrically: - A = rotation pi/2 anti-clockwise - B = reflection in the x-axis ]

  11. anonymous
    • 5 years ago
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    Thanks

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