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Thread: Help: Solve the following systems, where a, b, and c are constants.

  1. #1
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    Exclamation Help: Solve the following systems, where a, b, and c are constants.

    Mods plz remove this one, i have posted in the right section now, i didn't want a advanced linear algebra answer.


    This is a linear algebra question and i dont know how to solve for this because of the a,b, and c. i tried to do something but i dont know if its right.

    I get the answer for part b as
    x1 = a - c/3
    x2 = -2b + b + c/3
    x3 = 2a - b

    Plz help me out and try to explain a bit if you can. I need help on a and b both.

    Last edited by mastdesi; Jan 19th 2010 at 04:35 PM.
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  2. #2
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    Solve the following

    $\displaystyle
    \left[ \begin{array}{c}
    x_1\\
    x_2\\
    x_3\end{array}\right]=\left[ \begin{array}{ccc}
    1 & 1 & 1 \\
    2 & 0 & 2 \\
    0 & 3 & 3 \end{array} \right]^{-1} \left[ \begin{array}{c}
    a\\
    b\\
    c\end{array}\right]
    $
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  3. #3
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    we are suppose to do it using the row-echlon form, i used reduced row echlon since it easier most of the time and we have only been taught till reduced row-echlon form. so i dont know what you mean by the -1 there because we didn't learn that yet.
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  4. #4
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    Thumbs up Help: Solve the following systems, where a, b, and c are constants

    This is a linear algebra question and i dont know how to solve for this because of the a,b, and c. i tried to do something but i dont know if its right.


    I get the following answer using reduced row echlon for part b as
    x1 = a - c/3
    x2 = -2b + b + c/3
    x3 = 2a - b

    Plz help me out and try to explain a bit if you can. I need help on a and b both.

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  5. #5
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    http://www.mathhelpforum.com/math-he...constants.html

    You find the inverse of the matrix (the -1 part) by row echelon operations
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  6. #6
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    Quote Originally Posted by mastdesi View Post
    This is a linear algebra question and i dont know how to solve for this because of the a,b, and c. i tried to do something but i dont know if its right.


    I get the following answer using reduced row echlon for part b as
    x1 = a - c/3
    x2 = -2b + b + c/3
    x3 = 2a - b

    Plz help me out and try to explain a bit if you can. I need help on a and b both.

    (a) You can solve this by substitution, graphing or elimination.
    Substitution:
    $\displaystyle 2x + y = a \rightarrow y = -2x + a$
    plug $\displaystyle y = -2x + a$ into $\displaystyle 3x + 6y = b $ so ...
    $\displaystyle 3x + 6(-2x + a) = b$

    Solve
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