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liliy

  • 2 years ago

matrix: 2x+3y+ 7z= 13 3x+2y - 5z = -22 5x+7y - 3z = -28

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  1. liliy
    • 2 years ago
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    @phi can you help me?

  2. precal
    • 2 years ago
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    use elimination

  3. liliy
    • 2 years ago
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    what does that mean?

  4. precal
    • 2 years ago
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    multiply -3 to the first equation multiply 2 to the second equation

  5. liliy
    • 2 years ago
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    we have to use matrix

  6. precal
    • 2 years ago
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    idea is to get rid of one variable at a time matrix - even better can you put it in the calculator?

  7. precal
    • 2 years ago
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    |dw:1338861644110:dw|

  8. liliy
    • 2 years ago
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    hahah. no calculators.. this is linear algebra

  9. precal
    • 2 years ago
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    yes, well the idea is still the same except with not using the variables

  10. precal
    • 2 years ago
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    sorry it has been a long time since I have done linear algebra. I just remember it was my favorite course during my undergrad days....... :)

  11. liliy
    • 2 years ago
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    i dont understand the matrix . can you brief me, i feel like my numbers are always wrong and then the whole thing is wrong

  12. liliy
    • 2 years ago
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    if i get a matrix of numbers and when it simplifies: 1 0 3 8 0 0 9 3 0 0 8 9

  13. liliy
    • 2 years ago
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    these are arbitrarty numbers but if i get two rows that have 0 0 does that mean its bad?

  14. precal
    • 2 years ago
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    |dw:1338861963247:dw| this is your goal in the end

  15. precal
    • 2 years ago
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    if it has a solution

  16. liliy
    • 2 years ago
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    right, but if you have any rows that are all zeros that means what?

  17. precal
    • 2 years ago
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    |dw:1338862078583:dw|

  18. liliy
    • 2 years ago
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    k, like:: 2 4 6 -8 3 6 7 10

  19. precal
    • 2 years ago
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    this one has a solution x=-1, y=-2, z=3

  20. precal
    • 2 years ago
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    |dw:1338862146454:dw| you goal is to create that solution form (sorry I can't even remember its official name, may I be forgiven by the math gods) I would multipy the first row by (1/2) that would force that first term to turn into a 1 but don't forget to change all the other numbers in that row

  21. precal
    • 2 years ago
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    I think that is called row multiplication

  22. precal
    • 2 years ago
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    http://www.wyzant.com/Help/Math/Precalculus/Systems_Of_Equations/Matrix_Method.aspx

  23. liliy
    • 2 years ago
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    got it, but for the little example i just posted: 2 4 6 -8 3 6 7 10, this matrix, i get the bottom row is 0 0 .. and none of the multiple choices look like that, what am i doing wrong?

  24. precal
    • 2 years ago
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    not sure, I put it in my calculator and it does have a solution

  25. precal
    • 2 years ago
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    sorry reposted your question but label it, must use the matrix (linear algebra) good luck :) sorry

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