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anonymous

  • one year ago

what is the solution of the matrix ?

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  1. anonymous
    • one year ago
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  2. xapproachesinfinity
    • one year ago
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    do you have to do it with matrices?

  3. anonymous
    • one year ago
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    um i think soo , would you do this the same way you would do it if it was addtion ?if that makes sense

  4. anonymous
    • one year ago
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    addition *

  5. anonymous
    • one year ago
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    ill show you what im talking about

  6. anonymous
    • one year ago
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    this is what i am talking about would i do it the same but just multiply ?

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  7. xapproachesinfinity
    • one year ago
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    not really getting your point inverse of 2x2 matrix can be computed like this |dw:1433291928663:dw|

  8. xapproachesinfinity
    • one year ago
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    i see your point, you need inverse and them multiplciation operation of matrices there is not addition here

  9. perl
    • one year ago
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    $$\Large {A}\mathbf{ x} = \mathbf{b} \\ \Large \mathbf{ x} = A^{-1} \mathbf{b}$$

  10. anonymous
    • one year ago
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    I know ...... :(((((

  11. xapproachesinfinity
    • one year ago
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    try to find the determinant first

  12. anonymous
    • one year ago
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    now how would i find that , i usually use a online matrix calculator to find the determinant so i wouldn't know how to find on my own

  13. xapproachesinfinity
    • one year ago
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    ok the determinant is computed like this |dw:1433292400098:dw|

  14. anonymous
    • one year ago
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    ok

  15. xapproachesinfinity
    • one year ago
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    you multiply ad and bc and then subtract

  16. anonymous
    • one year ago
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    ok thats all ?

  17. xapproachesinfinity
    • one year ago
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    do the same with your matrix

  18. xapproachesinfinity
    • one year ago
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    no not finished that's only how to do determinant

  19. anonymous
    • one year ago
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    ok im writing this down

  20. xapproachesinfinity
    • one year ago
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    ok

  21. anonymous
    • one year ago
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    cross multiply ?

  22. xapproachesinfinity
    • one year ago
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    yeah seems like cross multiply then take the difference

  23. anonymous
    • one year ago
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    so for me it would me 9*1 &4*2 for A and for X it would be -9*-8 and -6 *-1 right?

  24. anonymous
    • one year ago
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    or did you mean multiply A with X ???

  25. xapproachesinfinity
    • one year ago
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    so here \[A=\begin{bmatrix}9&4\\ 2&1\end{bmatrix}\] \[\det(A)=9(1)-2(4)=9-8=1\]

  26. xapproachesinfinity
    • one year ago
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    oh no what are you taling about? are you following what i'm saying haha

  27. anonymous
    • one year ago
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    yeah

  28. anonymous
    • one year ago
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    9*1 i did that 2*4 i did that too

  29. xapproachesinfinity
    • one year ago
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    we are looking for X and i used what perl did X=Ainverse times B

  30. anonymous
    • one year ago
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    i know what i did wrong i forgot to subtract ..

  31. xapproachesinfinity
    • one year ago
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    it was AX=B then we multiplied A^-1 and we got X=A^{-1}B now we are in the process of computing A inverse that is why we need determinant of A

  32. xapproachesinfinity
    • one year ago
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    no seems you missed the whole poiint from what i understand from your last reply

  33. anonymous
    • one year ago
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    no .. i didn't you said cross multiply then subtract right ???

  34. xapproachesinfinity
    • one year ago
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    that's only for determinant

  35. xapproachesinfinity
    • one year ago
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    i did that for you already see my replay above

  36. xapproachesinfinity
    • one year ago
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    \(\color{blue}{\text{Originally Posted by}}\) @xapproachesinfinity so here \[A=\begin{bmatrix}9&4\\ 2&1\end{bmatrix}\] \[\det(A)=9(1)-2(4)=9-8=1\] \(\color{blue}{\text{End of Quote}}\)

  37. anonymous
    • one year ago
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    ok so what do have to do next then ?

  38. anonymous
    • one year ago
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    find x ?

  39. xapproachesinfinity
    • one year ago
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    |dw:1433293368759:dw|

  40. anonymous
    • one year ago
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    yup

  41. xapproachesinfinity
    • one year ago
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    so we do 1/det A so 1/1 =1 here we didn't need to worrt about it since it is just 1

  42. anonymous
    • one year ago
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    ok

  43. xapproachesinfinity
    • one year ago
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    next step is to do a switch|dw:1433293517899:dw|

  44. xapproachesinfinity
    • one year ago
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    you take A and switch a and d b and no switch you just change the sign

  45. anonymous
    • one year ago
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    ok i get that but where do the negatives come from

  46. xapproachesinfinity
    • one year ago
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    it is a rule you need to read about it on your notes

  47. xapproachesinfinity
    • one year ago
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    what kind of class are taking

  48. anonymous
    • one year ago
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    algebra 2

  49. xapproachesinfinity
    • one year ago
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    hmm really? i don't really know how much you know about matrices

  50. xapproachesinfinity
    • one year ago
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    hmm this really needs some time to get accustomed to! it may be fairly easy, but needs a lot of practice you might want to look at some video tutorial on youtube

  51. anonymous
    • one year ago
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    okay , i will

  52. xapproachesinfinity
    • one year ago
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    once you feel comfortable then tackle problem it is no helping to do problem you are not ready to do be real, no matter how much i explain to you here, you will need the lecture first here open study will not give you the lecture rather help assist you with difficulties you are having after knowing the lecture and know fairly enough on the subject

  53. xapproachesinfinity
    • one year ago
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    i will do your problem now, but next problem you need to try your hardest :)

  54. anonymous
    • one year ago
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    okay

  55. xapproachesinfinity
    • one year ago
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    let me do it on paper ans take a picture

  56. anonymous
    • one year ago
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    ok

  57. xapproachesinfinity
    • one year ago
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    almost hehe

  58. anonymous
    • one year ago
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    kay

  59. xapproachesinfinity
    • one year ago
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  60. xapproachesinfinity
    • one year ago
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    before the last line i preformed matrix multiplication

  61. xapproachesinfinity
    • one year ago
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    is it readable ?

  62. anonymous
    • one year ago
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    yeah it is . -5 ,26 -9 and -60 correct right

  63. xapproachesinfinity
    • one year ago
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    there is no -9

  64. anonymous
    • one year ago
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    oh ,

  65. xapproachesinfinity
    • one year ago
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    that's just brackets

  66. xapproachesinfinity
    • one year ago
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    that should match C

  67. anonymous
    • one year ago
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    oh , my bad it looked like a negative for a second but yes it is C

  68. xapproachesinfinity
    • one year ago
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    okay

  69. xapproachesinfinity
    • one year ago
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    hope that helps

  70. anonymous
    • one year ago
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    it does ,,,,, THANKS ..

  71. xapproachesinfinity
    • one year ago
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    my pleasure

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