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    (\frac{d^2}{dx^2}+n^2)y=0

    Alright so I've done quite a bit of calculus but I have never seen this notation before... What is it on about?! Second derivative of what?
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    (Original post by 2.7182818)
    (\frac{d^2}{dx^2}+n^2)y=0

    Alright so I've done quite a bit of calculus but I have never seen this notation before... What is it on about?! Second derivative of what?
    Expand the bracket and you get the second derivative of y.
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    It's not that simple is it? Taking derivatives is a seperate function to multiplication, is the bracket indicating both?
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    Is there anything (in the working) before it? I might be able to explain it if I can see all the working.
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    Solve the following differential equations (subject to the conditions y(0)=0, dy/dx(0)=1 ... It is probably just as Mr. M said, just seems a bit too easy for my liking, seeing as the question before was
    xy\frac{dy}{dx}+(x^2+y^2+x)=0 ...
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    (Original post by 2.7182818)
    (\frac{d^2}{dx^2}+n^2)y=0
    You might like to think about the sum of two squares. Can we factorise further?
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    (Original post by Mr M)
    You might like to think about the sum of two squares. Can we factorise further?
    Errr do we need to? If it did mean d2y/dx2 than just use auxiliary equation and get the answer in 2 lines...
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    (Original post by 2.7182818)
    Errr do we need to? If it did mean d2y/dx2 than just use auxiliary equation and get the answer in 2 lines...
    You have no sense of fun.

    (\frac{d}{dx} + ni)(\frac{d}{dx} - ni)y = 0

    \frac{dy}{dx} = \pm iny
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    (Original post by Mr M)
    You have no sense of fun.

    (\frac{d}{dx} + ni)(\frac{d}{dx} - ni)y = 0

    \frac{dy}{dx} = \pm iny
    Can't... unfortunately is + not - otherwise it would certainly add a slight flicker of interest to a extremely dull question. special moment...

    Here's a slightly more fun one...I've got an answer but if you wanna have a go to check it then feel free!

    (ln y - x) \frac{dy}{dx} - y ln y = 0
 
 
 
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