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    Here's the question:

    Find \frac{\partial f}{\partial x})_y for f(x,y)=\frac{x^2u+1}{axy}, assuming that there are no implicit functions of the given variables.

    Using the quotient rule:

    u=x^2u+1 \rightarrow \frac{\partial u}{\partial x}=2xu+x^2\frac{\partial u}{\partial x}
    v=axy \rightarrow  \frac{\partial v}{\partial x}=\frac{\partial a}{\partial x}xy+ay
    \frac{\partial f}{\partial x}=\frac{axy(2xu+x^2 \frac{\partial u}{\partial x})-y(x^2u+1)(\frac{\partial a}{\partial x}x+a)}{a^2x^2y^2}

    (I know the above working is a bit confusing because I used the u in the quotient rule as well as it being a variable but I hope it's clear what I did.)

    I just wanted to see if this is right to make sure I actually know what I'm doing... thanks!
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    Your working seems OK to me. Have you covered the multivariable chain rule yet? That is \frac{\partial f}{\partial u} = \frac{\partial f}{\partial x}\frac{\partial x}{\partial u} + \frac{\partial f}{\partial y}\frac{\partial y}{\partial u}. Questions on this topic involving the chain rule are more common (and make things a little more complicated), so I'd practice those too.
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    (Original post by A Slice of Pi)
    Your working seems OK to me. Have you covered the multivariable chain rule yet? Questions involving chain rule are more common, so I'd practice those too.
    http://www.thestudentroom.co.uk/show....php?t=3683635
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    That looks an interesting question. I'll be sure to have a go at that later...
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    (Original post by A Slice of Pi)
    That looks an interesting question. I'll be sure to have a go at that later...
    https://www0.maths.ox.ac.uk/system/f...us_Sheet_3.pdf
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    can you please post 1 and 2 and feel free to post anything else ...
    in fact give us the password!
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    (Original post by TeeEm)
    can you please post 1 and 2 and feel free to post anything else ...
    in fact give us the password!
    They're all here https://www0.maths.ox.ac.uk/courses/material , you don't need a password or anything to access it
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    (Original post by Gome44)
    They're all here https://www0.maths.ox.ac.uk/courses/material , you don't need a password or anything to access it
    amazing!!!
    undergrad material is usually hard to find
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    (Original post by TeeEm)
    amazing!!!
    undergrad material is usually hard to find
    There are some cambridge sheets here as well http://www.damtp.cam.ac.uk/user/examples/, but they are only for certain modules
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    (Original post by Gome44)
    There are some cambridge sheets here as well http://www.damtp.cam.ac.uk/user/examples/, but they are only for certain modules
    thanks
 
 
 
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