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angela210793

Matrix

  • 2 years ago
  • 2 years ago

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  1. angela210793
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    I thought to multiply the first row with 1/3...|dw:1329578934017:dw|

    • 2 years ago
  2. nenadmatematika
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    that would be a good idea angela :D

    • 2 years ago
  3. angela210793
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    i can make the first element in the second row 0 but i can't go further :(

    • 2 years ago
  4. bahrom7893
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    what's r? reduced row echelon?

    • 2 years ago
  5. angela210793
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    idk wht u call it...i'm asking for the range

    • 2 years ago
  6. nenadmatematika
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    why? multiply the first row with -4 and add to the third row to get 0 under

    • 2 years ago
  7. amistre64
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    colA is the range of a matrix A right?

    • 2 years ago
  8. amistre64
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    row reduce to determine your pivot points; and all columns with a pivot point define colA

    • 2 years ago
  9. angela210793
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    I'm sorry i don't get it..wht is colA???

    • 2 years ago
  10. amistre64
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    as far as I can tell, thats the american version of range of a matrix

    • 2 years ago
  11. nenadmatematika
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    |dw:1329579146175:dw|

    • 2 years ago
  12. amistre64
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    can you type in the rows? a b c d e f g h like that cause its hard to read .... well, nenands is a bit clearer

    • 2 years ago
  13. nenadmatematika
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    |dw:1329579294854:dw|

    • 2 years ago
  14. amistre64
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    your matrix I believe will simplify to 3 linearly independant column vectors; or less. that will tell us the range or span

    • 2 years ago
  15. angela210793
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    :O:O:O:O How nenad?????? in the example my teacher has solved she has had the elements of the diagonal =1 :O

    • 2 years ago
  16. angela210793
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    has made***

    • 2 years ago
  17. amistre64
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    turning it into row reduced is extra work becasue the pivots dont change

    • 2 years ago
  18. nenadmatematika
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    no Angela I'm sure this is the solution...it's quite easy...do you know the procedure to get the rank of the matrix?

    • 2 years ago
  19. angela210793
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    i know the theory but i don't know how to use tht in practice -_-

    • 2 years ago
  20. angela210793
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    how did u know u should have changed R1with R3???

    • 2 years ago
  21. nenadmatematika
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    well this is how you start...first you take a look at the first element of the matrix (first row and the first column)....if it's different from zero then you call it ''the pivot''. OK? Now you make zeros under that first pivot using muliplication with some number and adding to the row below....that's how you make the zeros under the first pivot. Then you look for another pivot...you follow the main diagonal and if it's different from zero then it's a second pivot and you make zeros under that number...you continue with this procedure until you're finished....the final rank is the number of elements on the main diagonal different from zero, so the number of pivots...in this case I have three pivots so the rank is 3

    • 2 years ago
  22. angela210793
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    Hmmmm.....ok thanks guys :):)

    • 2 years ago
  23. nenadmatematika
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    >> rank([3 6 9 3;2 -5 3 0;4 -10 10 4]) ans = 3

    • 2 years ago
  24. nenadmatematika
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    Matlab says it's 3 also so your teacher is tripping :D

    • 2 years ago
  25. angela210793
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    I'm really hopeless...:(:( thank you very much :) both of u :)

    • 2 years ago
  26. nenadmatematika
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    angela don't go...I can show you some examples so you can learn the procedure? I can give you some matrix and we'll work on it together OK?

    • 2 years ago
  27. angela210793
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    yes yes yes :)

    • 2 years ago
  28. nenadmatematika
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    ok here is one for begining:|dw:1329580248289:dw|

    • 2 years ago
  29. nenadmatematika
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    now tell me what is the first element of this matrix and is it different from zero?

    • 2 years ago
  30. angela210793
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    since the first element f the matrix is 1 then the first element of R2 must be 0???

    • 2 years ago
  31. angela210793
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    is the rank 1?? O.o

    • 2 years ago
  32. angela210793
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    range***

    • 2 years ago
  33. nenadmatematika
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    OK it's 1...so that is the first pivot...now do some operations to make 0 under that 1....the easiest way is to multiply the first row with -3 and to the second row...draw that so I can see OK?

    • 2 years ago
  34. nenadmatematika
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    add*

    • 2 years ago
  35. angela210793
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    |dw:1329580611324:dw|

    • 2 years ago
  36. nenadmatematika
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    that's great...now since you made zero under that 1, the next step is to look for the next pivot(element different from zero) on the main diagonal....it's number -2....so you have to make zeros under that pivot...but since there are no more elements under that -2 the transformations are done and now you can read the rank of the matrix....the rank is the number of row where at least one element is different from zero, or you can count the number of pivots(elements on the main diagonal different from zero)...so what is the rank?

    • 2 years ago
  37. RagingSquirrel
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    *Clicks on question thinking it's about the matrix* DANGIT

    • 2 years ago
  38. nenadmatematika
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    number of rows*

    • 2 years ago
  39. angela210793
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    so the range is 2???

    • 2 years ago
  40. nenadmatematika
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    correct Angela!!! :D just to be clear here in Serbia we call it rang, but I read this material from the American matematicians and I'm sure they use the term ''rank''

    • 2 years ago
  41. angela210793
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    haha :) can we work on some more examples pleaseeeee

    • 2 years ago
  42. nenadmatematika
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    of course....check this one:|dw:1329580900431:dw|

    • 2 years ago
  43. angela210793
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    |dw:1329581058847:dw|

    • 2 years ago
  44. nenadmatematika
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    yes :D

    • 2 years ago
  45. angela210793
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    |dw:1329581078055:dw|

    • 2 years ago
  46. nenadmatematika
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    no...we must make a deal here....it's very important the way you make zeros...you can't do it anyway you want...first you make the zeros under that 1. So multiply the first row with -2 and add to the second row....in the third row you already have zero so you don't touch that third row OK.? draw again...:D

    • 2 years ago
  47. angela210793
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    no way :(:(|dw:1329581327917:dw|

    • 2 years ago
  48. nenadmatematika
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    great it's correct now what is the next pivot you see?

    • 2 years ago
  49. angela210793
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    10????

    • 2 years ago
  50. nenadmatematika
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    that's my girl....now make zeros under that pivot....

    • 2 years ago
  51. angela210793
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    xD just a thought...how abt R1-2R3???

    • 2 years ago
  52. angela210793
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    tht won't work will it???

    • 2 years ago
  53. nenadmatematika
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    you don't touch the first row anymore...you made zeros under the first pivot, so you now operate with the second row....for example multiply the second pivot with -1/5 and add to the third row...

    • 2 years ago
  54. nenadmatematika
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    |dw:1329581919090:dw|

    • 2 years ago
  55. angela210793
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    |dw:1329582143630:dw|

    • 2 years ago
  56. nenadmatematika
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    what is the third pivot now?

    • 2 years ago
  57. angela210793
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    5??? but there's no 0 under it O.o

    • 2 years ago
  58. nenadmatematika
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    that's right....that means no more transformations with the matrix so what is the rank?

    • 2 years ago
  59. angela210793
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    3??

    • 2 years ago
  60. nenadmatematika
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    yes

    • 2 years ago
  61. angela210793
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    ur a genius xD :) Can i borrow ur brain???????

    • 2 years ago
  62. nenadmatematika
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    wait we must do one more :D

    • 2 years ago
  63. angela210793
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    sure :)))

    • 2 years ago
  64. nenadmatematika
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    |dw:1329582383881:dw|

    • 2 years ago
  65. nenadmatematika
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    haha :D

    • 2 years ago
  66. angela210793
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    how abt R1-2R3???

    • 2 years ago
  67. nenadmatematika
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    no problem :D OK Angela what is the first number you see?

    • 2 years ago
  68. angela210793
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    |dw:1329582684252:dw|

    • 2 years ago
  69. angela210793
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    OMG wait.... will i be the stupid girl who didn't get a single thing? :O:O:O

    • 2 years ago
  70. nenadmatematika
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    OK I hope we both agree that is unconvenient to perform ''zero making'' under that 13...so one of the possibilities is to exchange the first and the third column because the third column is filled with ''beautiful numbers '' for addition, multiplication etc do it

    • 2 years ago
  71. angela210793
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    i was just going to ask if we could change C3 with C1 :)

    • 2 years ago
  72. angela210793
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    |dw:1329582859078:dw|

    • 2 years ago
  73. nenadmatematika
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    now you work and I watch....:D

    • 2 years ago
  74. angela210793
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    |dw:1329582907187:dw|

    • 2 years ago
  75. nenadmatematika
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    |dw:1329582876260:dw|

    • 2 years ago
  76. angela210793
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    |dw:1329583007088:dw|

    • 2 years ago
  77. angela210793
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    ahhhhaaaa...i just wanted ur confirmation ;) :P

    • 2 years ago
  78. angela210793
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    |dw:1329583049393:dw|

    • 2 years ago
  79. nenadmatematika
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    |dw:1329583024634:dw|

    • 2 years ago
  80. angela210793
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    |dw:1329583163929:dw|

    • 2 years ago
  81. nenadmatematika
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    |dw:1329583152017:dw|

    • 2 years ago