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Math Help - I need help with a fairly simple question

  1. #1
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    Solved! =D Thankyou! =

    Heya! =]

    Right now I'm down to the last question, but my brain isn't really helping me finish it off. :P

    The answer in the book says Y= 1, but I keep on getting Y=2.09

    So could you guys help me figure out how to solve it? =[

    This is the question:

    -2 -3y = x
    3x -2y = -17

    Find X and find Y.

    (Once I find one out, I can easily complete the other. )

    And this is how I carry it out:

    -2y + 3 (-2 -3y) = -17

    -2y -6 = -17

    -11y -6 = -17

    -11y = -23

    11y/11 = -23/11

    Therefore y = 2.09?

    But that's not right. =[

    Thanks in advance!
    Last edited by Hikaru; January 29th 2008 at 03:01 AM. Reason: Update
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  2. #2
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    Quote Originally Posted by Hikaru View Post
    Heya! =]

    Right now I'm down to the last question, but my brain isn't really helping me finish it off. :P

    The answer in the book says Y= 1, but I keep on getting Y=2.09

    So could you guys help me figure out how to solve it? =[

    This is the question:

    -2 -3y = x
    3x -2y = -17

    Find X and find Y.

    (Once I find one out, I can easily complete the other. )

    And this is how I carry it out:

    -2y + 3 (-2 -3y) = -17

    -2y -6 = -17 Mr F says: Wrong. It's -2y - 6 - 9y = -17. When you expanded the 3 (-2 - 3y) term, you forgot to multiply the 3 with the -3y .....!!

    -11y -6 = -17 Mr F says: Oh .... This is actually correct. So you didn't make the above mistake. You just didn't write it in.

    -11y = -23 Mr F says: OK, this is wrong. When you add the 6 to both sides, -17 + 6 = -11, NOT -23. So it should be -11y = -11. It clearly follows that y = 1.

    11y/11 = -23/11

    Therefore y = 2.09?

    But that's not right. =[

    Thanks in advance!
    ..
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  3. #3
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    Quote Originally Posted by mr fantastic View Post
    ..
    OHHHHH! Thankyou for that! =]

    My calculator died so I've been doing the calculations in my head, and totally forgot about that. Thanks for pointing that out!

    Take care! xox
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