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anonymous

  • one year ago

Need genius math people's help !!!!! There are two matrices A and B. A = 4 -6 B= 5 1 4 -2 -1 -3 I want to find a matrix D which satisfies A+B+D=I and I got below the answer but it said still wrong. -8 5 -3 6 Please help me people !!!!!!!!!!!!!!!!!

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  1. sdfgsdfgs
    • one year ago
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    I= 1 1 1 1 right? if so, then -8 and 6 are right, re-calculate the other two.

  2. anonymous
    • one year ago
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    Isn't I = 1 0 0 1 ???

  3. UsukiDoll
    • one year ago
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    yes a 2 x 2 identity matrix is 1 0 0 1

  4. UsukiDoll
    • one year ago
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    hmmm latex for matrices is nasty.. so we have this equation A+B+D=I where A and B matrices are given. so we need to find Matrix D

  5. sdfgsdfgs
    • one year ago
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    @taejunlee sorry u are right of cuz...been a while since i looked at matrix. so ur ans should be right then. may be someone else can help u. good luck! :)

  6. UsukiDoll
    • one year ago
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    what if we rearrange this equation for a bit D =I-A-B like that and then use matrix addition and matrix subtraction ?

  7. UsukiDoll
    • one year ago
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    |dw:1437187726707:dw|

  8. UsukiDoll
    • one year ago
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    now use matrix subtraction. @taejunlee

  9. UsukiDoll
    • one year ago
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    blah...... we can start with the first two matrices and then that result - matrix B

  10. UsukiDoll
    • one year ago
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    |dw:1437188093151:dw|

  11. anonymous
    • one year ago
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    so isn't answer -8 6 -2 6 ???

  12. UsukiDoll
    • one year ago
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    well let's check first... could you do the matrix in black (the one I drew) ?

  13. anonymous
    • one year ago
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    that is -3 6 -4 3

  14. UsukiDoll
    • one year ago
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    excellent now we just need to do matrix subtraction with matrix b hold on a sec .. need to draw

  15. UsukiDoll
    • one year ago
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    |dw:1437188427336:dw|

  16. anonymous
    • one year ago
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    and -8 5 -3 6....

  17. UsukiDoll
    • one year ago
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    which is the matrix you got in the first place... it should be right then. Why is it wrong?

  18. anonymous
    • one year ago
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    well.. that was what I thought.. I better ask professor ..

  19. UsukiDoll
    • one year ago
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    |dw:1437188557694:dw|

  20. UsukiDoll
    • one year ago
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    that should end up to 1 0 0 1

  21. UsukiDoll
    • one year ago
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    you got the right matrix. It must be some bug in the online homework or the professor's stupidity or something

  22. UsukiDoll
    • one year ago
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    |dw:1437188718111:dw|

  23. UsukiDoll
    • one year ago
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    |dw:1437188725475:dw|

  24. anonymous
    • one year ago
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    guess there is something wrong with online system.. anyways I really appreciate what you've done for me :)

  25. UsukiDoll
    • one year ago
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    hahah no problem :)

  26. sdfgsdfgs
    • one year ago
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    @taejunlee only thing i can think of is check the + signs in ur eqn n see if one may be a - instead.

  27. UsukiDoll
    • one year ago
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    @sdfgsdfgs he got the right matrix, so it wasn't the equation. It's some bug in his online stuff.

  28. sdfgsdfgs
    • one year ago
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    @UsukiDoll u are probably right - was just thinking may be the eqn should be A+B-D=I or something like that instead.

  29. Empty
    • one year ago
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    https://www.codecogs.com/latex/eqneditor.php

  30. UsukiDoll
    • one year ago
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    ^ matrix in latex is crummy, but thanks for the link. still I prefer to draw in this case.

  31. UnkleRhaukus
    • one year ago
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    \[\begin{align} \textbf A+\textbf B+\textbf D &=\textbf I\\[2ex] \begin{pmatrix}4&-6\\4&-2\end{pmatrix} +\begin{pmatrix}5&1\\-1&-3\end{pmatrix} +\begin{pmatrix}d_{00}&d_{01}\\d_{10}&d_{11}\end{pmatrix} &=\begin{pmatrix}1&0\\0&1\end{pmatrix}\\[2ex] \begin{pmatrix}4+5&-6+1\\4-1&-2-3\end{pmatrix} +\begin{pmatrix}d_{00}&d_{01}\\d_{10}&d_{11}\end{pmatrix} &=\begin{pmatrix}1&0\\0&1\end{pmatrix}\\[2ex] \begin{pmatrix}9&-5\\3&-5\end{pmatrix} +\begin{pmatrix}d_{00}&d_{01}\\d_{10}&d_{11}\end{pmatrix} &=\begin{pmatrix}1&0\\0&1\end{pmatrix}\\[2ex] \begin{pmatrix}d_{00}&d_{01}\\d_{10}&d_{11}\end{pmatrix} &=\begin{pmatrix}1&0\\0&1\end{pmatrix}-\begin{pmatrix}9&-5\\3&-5\end{pmatrix}\\[2ex] \begin{pmatrix}d_{00}&d_{01}\\d_{10}&d_{11}\end{pmatrix} &=\begin{pmatrix}1-9&0+5\\0-3&1+5\end{pmatrix}\\[2ex] \textbf D &=\begin{pmatrix}-8&5\\-3&6\end{pmatrix} \end{align}\]

  32. UsukiDoll
    • one year ago
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    wow that looks nice.

  33. UnkleRhaukus
    • one year ago
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    \[\begin{bmatrix}\circ&&\circ\\&\angle\\&\smile\end{bmatrix}\]

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