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Math Help - Make x the subject

  1. #1
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    Make x the subject

    Make x the subject:
    y = \frac{2x+7}{3x-1}

    I can't seem to make x the subject no matter how I re-arrange the equation.

    Can someone give me a hint as to where to start going about this?
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  2. #2
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    Do you mean solve for x when you say "make x the subject"? I'd say the first step is definitely to multiply both sides by 3x - 1.
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  3. #3
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    Quote Originally Posted by DavidM View Post
    Make x the subject:
    y = \frac{2x+7}{3x-1}

    I can't seem to make x the subject no matter how I re-arrange the equation.

    Can someone give me a hint as to where to start going about this?
    Multiply both sides by (3x-1), then expand all terms (you will get 3xy-y on the LHS), gather all terms with x in them on one side (move other terms to the other side), factor out the x, divide both sides by the quantity that x is multplying.
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  4. #4
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    I mean make x the subject as in:

    x = ?

    Re-arrange the formula to get x on its own.
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  5. #5
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    Got it, thanks undefined.

    x = \frac {y+7}{3y-2}
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  6. #6
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    Quote Originally Posted by DavidM View Post
    Got it, thanks undefined.

    x = \frac {y+7}{3y-2}
    you asked for a hint and then thank the guy who gave you the answer instead of a nudge in the right direction.
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  7. #7
    MHF Contributor undefined's Avatar
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    Quote Originally Posted by 1005 View Post
    you asked for a hint and then thank the guy who gave you the answer instead of a nudge in the right direction.
    There are many cases of unbalanced thanks here on the forum, sometimes I'm unduly appreciated, sometimes underappreciated, it is what it is.

    I agree that your reply does more of what the OP asked than mine and that you deserve credit.

    If anyone wants a (somewhat lengthy) explanation of my action, it is: I just made a judgment call that the question was of the "you either see it or you don't" type or "there's a trick to it" type, and that the response "here's the trick; observe" could be useful to the OP; also, I made a response that I thought would be helpful to me if I were in the OP's position; and I have no opinion on whether giving a "very large hint" like mine or a small hint like 1005's is better or worse, or right or wrong, to me they're just different approaches of people who want to help out.
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