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Math Help - Help with rref function

  1. #1
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    Help with rref function

    I have a Ti30x and my instructor is telling me that I need to perform this problem using the rref function, which the Ti30x doesnt have. I have to show a ck for my solution also. Can anybody help?

    10x+6y+z=7
    5x-9y-2z=3
    15x-12y+2z=-5

    Thank you In advance!!
    Todd
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    Quote Originally Posted by Firefightinfool View Post
    I have a Ti30x and my instructor is telling me that I need to perform this problem using the rref function, which the Ti30x doesnt have. I have to show a ck for my solution also. Can anybody help?

    10x+6y+z=7
    5x-9y-2z=3
    15x-12y+2z=-5
    Is this what you have? I doubt it can do matrices at all, given the single-line output. You will probably have to row-reduce by hand, but this particular problem should be fairly easy (it's only a 3x3, after all).
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  3. #3
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    Yes, its the Ti30IIS.
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    Im asking if you could complete it for me?
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    Quote Originally Posted by Firefightinfool View Post
    10x+6y+z=7
    5x-9y-2z=3
    15x-12y+2z=-5
    My 89 gives

    \left[\begin{matrix}<br />
1&0&0&3/5\\<br />
0&1&0&2/3\\<br />
0&0&1&-3<br />
\end{matrix}\right].
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  6. #6
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    Quote Originally Posted by Firefightinfool View Post
    I have a Ti30x and my instructor is telling me that I need to perform this problem using the rref function, which the Ti30x doesnt have. I have to show a ck for my solution also. Can anybody help?

    10x+6y+z=7
    5x-9y-2z=3
    15x-12y+2z=-5

    Thank you In advance!!
    Todd
    Hi Firefightinfool,

    I don't know about the TI30x, but on a TI-84+, you simply enter the matrix into your calculator, say Matrix A. I assume you can do that. You'll use the coefficients and the constant like

    \left(\begin {array}{cccc}10 & 6 & 1 & 7 \\ 5 & -9 & -2 & 3 \\ 15 & -12 & 2 & -5 \\ \end {array}\right)

    Then find your rref( ) (Reduced Row Echelon Form).

    On a TI-84 its under matrix math.

    Just enter rref([A]) and read the last column for your solutions.

    You should get \left\{\frac{3}{5}, \frac{2}{3}, -3\right\}

    If THIS is what the face of your calculator looks like, I don't see a way to enter a matrix array. Just not familiar with this model.
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    what is the syntax for entering that matrix in the TI-89 when using rref()?

    (ie.. [x,y,z],[x1,y1,z1])
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  8. #8
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    Quote Originally Posted by zepto- View Post
    what is the syntax for entering that matrix in the TI-89 when using rref()?

    (ie.. [x,y,z],[x1,y1,z1])
    If you have the system of equations:

    \begin{array}{rcl}x+2y&=&3 \\ 4x+5y&=& 6\end{array}

    then you find the command rref( at MATH(=2ND 5) MATRIX rref( or you choose the command rref( with the catalog.

    I've attached screenshots where you can find the command and how you type in the coefficients.
    Attached Thumbnails Attached Thumbnails Help with rref function-rref_ti89.png  
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