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DestisaurusRex Group Title

How would you find the determinant of : ⎡3 2⎤ ⎣6 4⎦ Without using a calculator?

  • 10 months ago
  • 10 months ago

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  1. TheRealMeeeee Group Title
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    ok You actually do it the same way for any size matrix: you pick a row and column, and multiply the value for each element in the row by the "cofactor" or "minor" (the smaller determinant found by eliminating the row and the column of the element that you're working with). | 5 2 0 0 -2 | | 0 1 4 3 2 | | 0 0 2 6 3 | | 0 0 3 4 1 | | 0 0 0 0 2 | This particular matrix is pretty easy, because it has a lot of zeros. So if you start with the last row, you get: 2 x | 5 2 0 0 | | 0 1 4 3 | | 0 0 2 6 | | 0 0 3 4 | Then, using the first column, you'd get: 2 x 5 x | 1 4 3 | | 0 2 6 | | 0 3 4 | Then again using the first column: 2 x 5 x 1 x | 2 6 | | 3 4 | 2 x 5 x 1 x (2 x 4 - 3 x 6) = -100

    • 10 months ago
  2. TheRealMeeeee Group Title
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    do this help

    • 10 months ago
  3. GirlByte Group Title
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    @DestisaurusRex lol do not listen to this guy ^^^ he copies answers! he got it from here http://answers.yahoo.com/question/index?qid=20070123154335AAIVKZd

    • 10 months ago
  4. TheRealMeeeee Group Title
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    omg no idid not u just a stalker

    • 10 months ago
  5. GirlByte Group Title
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    Yes you did.You have the same words plus you did the same thing to the other questions.

    • 10 months ago
  6. GirlByte Group Title
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    And its obvious its not from you cause you dont even know basic grammar

    • 10 months ago
  7. TheRealMeeeee Group Title
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    omg girl no i didnt not stalker

    • 10 months ago
  8. alekos Group Title
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    she's right i'm afraid

    • 10 months ago
  9. alekos Group Title
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    leave maths to the real mathematicians

    • 10 months ago
  10. alekos Group Title
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    for a 2x2 determinant \[\left[\begin{matrix}a & b \\ c & d\end{matrix}\right]\] it's ad - bc

    • 10 months ago
  11. alekos Group Title
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    no calculator required. should be able to do it in your head

    • 10 months ago
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