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-   -   Super Awesome Math Ques. (5) (https://www.askmehelpdesk.com/showthread.php?t=318619)

  • Feb 17, 2009, 02:34 PM
    EuRa
    Super Awesome Math Ques. (5)
    OK NM, I figured out the problem, ty.
  • Feb 17, 2009, 02:57 PM
    ebaines

    Hello Mike. The short way to solve: recognize that the only way A could have a known value is if the third equation is a linear combination of the first two. So, you show that it isn't, and hence conclude that the value for A can't be determined from the data you've been given.

    The long way: try one of the proposed values for A and solve the 3 equations in 3 unknowns to determine X, Y and Z. Then do it again with a different value of A, and see that the values of X, Y and Z are different. Hence A cannot be determined.
  • Feb 17, 2009, 03:18 PM
    EuRa
    Nm
  • Feb 17, 2009, 03:40 PM
    ebaines

    Quote:

    Originally Posted by EuRa View Post
    Actually it can be solved. I will show you how. Feel free to take another crack at it.

    Oops - I now see that the third equation is indeed a linear combination of the first two, if A = -6. Did this by calculating the determinant of the matrix of coefficients and setting it = 0 then solve for A.
  • Feb 17, 2009, 03:40 PM
    EuRa

    Actually... wait a minute. I thought I solved it but then I tried it again, and I was wrong. Maybe I didn't... ooh you might be right!
  • Feb 17, 2009, 03:55 PM
    EuRa

    Omg ebaines.. I think you were right the first time I believe! I thought I solved it, and I just tried it out, and I was entirely WRONG! Ty!!

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