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Thread: Quadratic Simultaneous Eqns: ""J and T share money. If I square J's money and add..."

  1. #21
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    Quote Originally Posted by Jonathan View Post
    I reduced the equation to
    (j−t)(j+t−1) = 2 x 5 x 5 x 149
    and spotted factors 50 x 149 "by inspection", it did not require "extensive trial and error".
    At least as quick as all the steps above.
    Fair enough. But you had said you did not get very far with substitution. Numerous methods work after substitution.

  2. #22
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    Quote Originally Posted by Jonathan View Post
    I'm still not sure about how much one can give away immediately. I think that unless we know that the question in the OP was homework to practice substitution there's little point pursuing that path. Especially as it leads to to an awkward quartic.
    In j^2 - t^2 + t - y = 10050 - 2600, I grouped the expressions on the left, saw "difference of two squares" so then could factorise with just two factors.
    Saw which pair of values matched the factors of 10050 - 2600.
    Must admit I assumed a whole number of dollars.
    Hi Jonathan - so you think this is the most straightforward approach?

    I know that the difference of two squares can be expressed as (j+t)(t-j) or (j-t)(t+j) ? Is this correct?

  3. #23
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    Quote Originally Posted by Jim77 View Post
    Hi Jonathan - so you think this is the most straightforward approach?

    I know that the difference of two squares can be expressed as (j+t)(t-j) or (j-t)(t+j) ? Is this correct?
    No no, (j+t)(t-j) and (j-t)(t+j) are not the same. j+t and t+j are the same. So for you to be correct it must be that t-j = j-t which is not true. For example. 9-7=2 while 7-9 = -2
    A mathematician is a blind man in a dark room looking for a black cat which isnít there. - Charles R. Darwin

  4. #24
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    Quote Originally Posted by Jim77 View Post
    Hi Jonathan - so you think this is the most straightforward approach?

    I know that the difference of two squares can be expressed as (j+t)(t-j) or (j-t)(t+j) ? Is this correct?
    Trying to post an answer - keep getting Error 500.
    Last edited by Jonathan; 03-06-2018 at 11:46 AM.

  5. #25
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    test

    Edit: I'm lucky...no error 500; however, I did get it a few times in the past...
    It also says that Subhotosh is busy having pizza: right?!!
    Last edited by Denis; 03-07-2018 at 10:33 AM.
    I'm just an imagination of your figment !

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