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DestisaurusRex

  • one year ago

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

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  1. TheRealMeeeee
    • one year ago
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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

  2. TheRealMeeeee
    • one year ago
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    do this help

  3. GirlByte
    • one year ago
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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

  4. TheRealMeeeee
    • one year ago
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    omg no idid not u just a stalker

  5. GirlByte
    • one year ago
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    Yes you did.You have the same words plus you did the same thing to the other questions.

  6. GirlByte
    • one year ago
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    And its obvious its not from you cause you dont even know basic grammar

  7. TheRealMeeeee
    • one year ago
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    omg girl no i didnt not stalker

  8. alekos
    • one year ago
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    she's right i'm afraid

  9. alekos
    • one year ago
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    leave maths to the real mathematicians

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

  11. alekos
    • one year ago
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    no calculator required. should be able to do it in your head

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