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Maths C4 - Integration... Help??? Watch

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    (Original post by Philip-flop)
    Yeah I know how to integrate by using the fact that...  \int \frac{f'(x)}{f(x)} dx = ln |f(x)| + c but I wasn't sure how I would do this by Substitution that's all
    Let u=\text{the denominator}
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    Philip-flop For C4 integration, to target the top grades you not only need to know all the integration methods but also be able to spot the best method to use since they won't always tell you in the exam. I've attached a list of integrals that you might like to look at. With these it's just as important to be able to see what the best method is than to actually do the integration. A student who can go through all of these and see what the best method is without trying different methods is a C4 integration expert in my eyes.

    They are all C4 level although a few of them are probably too hard to be in a C4 exam. One of them is actually impossible but it's a good exercise to try and find which one that is!

    EDIT: I'm not sure why \int \frac{\sqrt{x^2+4}}{x} \ dx is there - it's beyond C4.
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    (Original post by RDKGames)
    Let u=\text{the denominator}
    Ah yeah that's what I originally did but then cocked up in my workings, I've managed to do it though. I think I need to let my brain rest for the night now.

    (Original post by notnek)
    Philip-flop For C4 integration, to target the top grades you not only need to know all the integration methods but also be able to spot the best method to use since they won't always tell you in the exam. I've attached a list of integrals that you might like to look at. With these it's just as important to be able to see what the best method is than to actually do the integration. A student who can go through all of these and see what the best method is without trying different methods is a C4 integration expert in my eyes.

    They are all C4 level although a few of them are probably too hard to be in a C4 exam. One of them is actually impossible but it's a good exercise to try and find which one that is!

    EDIT: I'm not sure why \int \frac{\sqrt{x^2+4}}{x} \ dx is there - it's beyond C4.
    Thanks for these notnek turns out I was just having a right nightmare with the substitution - I guess it's a sign that I should have more breaks when I'm studying!

    I managed to solve  \int \frac{3x}{2x^2+4} dx by doing Integration by Substitution and also by using the fact that  \int \frac{f'(x)}{f(x)} dx = ln |f(x)| + c

    Looking forward to solving the ones you've attached
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    It could be worse mate

    You could be doing a maths degree where you have to do double integrals lol
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    (Original post by fefssdf)
    It could be worse mate

    You could be doing a maths degree where you have to do double integrals lol
    They aren't that bad, just one variable at a time.
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    (Original post by notnek)
    Philip-flop For C4 integration, to target the top grades you not only need to know all the integration methods but also be able to spot the best method to use since they won't always tell you in the exam. I've attached a list of integrals that you might like to look at. With these it's just as important to be able to see what the best method is than to actually do the integration. A student who can go through all of these and see what the best method is without trying different methods is a C4 integration expert in my eyes.

    They are all C4 level although a few of them are probably too hard to be in a C4 exam. One of them is actually impossible but it's a good exercise to try and find which one that is!

    EDIT: I'm not sure why \int \frac{\sqrt{x^2+4}}{x} \ dx is there - it's beyond C4.
    One last thing, do you have corresponding answers for these so I check whether I'm right?
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    (Original post by RDKGames)
    They aren't that bad, just one variable at a time.
    It's longggggg
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    (Original post by Philip-flop)
    One last thing, do you have corresponding answers for these so I check whether I'm right?
    I think I used to but I don't anymore sorry. You can always use Wolfram Alpha to check your answers or you could ask here.
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    (Original post by RDKGames)
    They aren't that bad, just one variable at a time.
    What about  \displaystyle \int_0^4\int_{\sqrt x}^2 \frac{1}{1+y^3} \ dydx don't even think it's fricking possible son.
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    (Original post by Ano9901whichone)
    What about  \displaystyle \int_0^4\int_{\sqrt x}^2 \frac{1}{1+y^3} \ dydx don't even think it's fricking possible son.
    Okay MOST double integrals aren't that bad.
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    (Original post by RDKGames)
    Okay MOST double integrals aren't that bad.
    Oh I was joking it's actually quite easy. Change order of integration to get  \displaystyle \int_0^2 \int_{0}^{y^2} \frac{1}{1+y^3} \ dxdy need I say anymore.
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    (Original post by Ano9901whichone)
    Oh I was joking it's actually quite easy. Change order of integration to get  \displaystyle \int_0^4 \int_{0}^{y^2} \frac{1}{1+y^3} \ dxdy need I say anymore.
    See why didn't you just give this one instead? Too late in the evening to think
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    (Original post by Ano9901whichone)
    What about  \displaystyle \int_0^4\int_{\sqrt x}^2 \frac{1}{1+y^3} \ dydx don't even think it's fricking possible son.
    (Original post by Ano9901whichone)
    Oh I was joking it's actually quite easy. Change order of integration to get  \displaystyle \int_0^4 \int_{0}^{y^2} \frac{1}{1+y^3} \ dxdy need I say anymore.
    Those aren't the same.
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    Click on a C4 thread and everyone is talking about double integrals, standard.
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    (Original post by RDKGames)
    See why didn't you just give this one instead? Too late in the evening to think
    Cos that would be too easy.
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    (Original post by Zacken)
    Those aren't the same.
    Alright Gauss I've edited the typo now.
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    (Original post by 13 1 20 8 42)
    Click on a C4 thread and everyone is talking about double integrals, standard.
    Welcome to TSR.
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    (Original post by 13 1 20 8 42)
    Click on a C4 thread and everyone is talking about double integrals, standard.
    It's just integrals though so it's all the same.
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    (Original post by Ano9901whichone)
    It's just integrals though so it's all the same.
    It's not C4 level
    What if the A-level students get scared
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    (Original post by 13 1 20 8 42)
    It's not C4 level
    What if the A-level students get scared
    Let them be scared. + they should know this is obviously not on the spec.
 
 
 
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