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    How do I work out

    dy/dx + 9 = x(y-3)

    I think its a first order differential equation but I'm not entirely sure about how to tackle this

    Thanks
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    (Original post by SpaceBunny)
    How do I work out

    dy/dx + 9 = x(y-3)

    I think its a first order differential equation but I'm not entirely sure about how to tackle this

    Thanks
    What methods do you know to solve first order differential equations?
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    (Original post by SeanFM)
    What methods do you know to solve first order differential equations?
    Methods? You mean like collecting all y terms onto one side and x on the other?
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    (Original post by SpaceBunny)
    Methods? You mean like collecting all y terms onto one side and x on the other?
    That sounds like a good one to use. :borat:
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    (Original post by SeanFM)
    That sounds like a good one to use. :borat:
    But I keep getting thrown off by that 9, really annoying me
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    (Original post by SpaceBunny)
    But I keep getting thrown off by that 9, really annoying me
    Woops, I was on autopilot, sorry!

    Maybe seperating the variables isn't the way to go, and you may be better off expanding x(y-3) before using another method.
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    (Original post by SeanFM)
    Woops, I was on autopilot, sorry!

    Maybe seperating the variables isn't the way to go, and you may be better off expanding x(y-3) before using another method.
    Ahh okay, thanks
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    (Original post by SpaceBunny)
    How do I work out

    dy/dx + 9 = x(y-3)

    I think its a first order differential equation but I'm not entirely sure about how to tackle this

    Thanks
    Maybe multiply both sides by 1 / (y-3) and then multiply both sides by dx. Then take the integral of both sides and then get y on it's own.Not sure if what I said is even remotely related to working out the equation but that's all I could think of.
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    (Original post by SeanFM)
    Woops, I was on autopilot, sorry!

    Maybe seperating the variables isn't the way to go, and you may be better off expanding x(y-3) before using another method.
    According to Wolfram, this can't be solved in terms of elementary functions
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    (Original post by Indeterminate)
    According to Wolfram, this can't be solved in terms of elementary functions
    :facepalm: that explains why I haven't been able to do it for the past few minutes. (Well, one of the reasons...)

    Sorry, OP! :getmecoat:
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    (Original post by SeanFM)
    :facepalm: that explains why I haven't been able to do it for the past few minutes.

    Sorry, OP! :getmecoat:
    I am pretty sure you have to integrate both sides simultaneously, after you get y and dy, and x and dx on separate sides of the equal sign.
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    this is a standard 1st order ODE which can be solved in 2 different ways using techniques available to further mathematicians
 
 
 
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