C3 (Not MEI) - Thursday June 14 2012, AM

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  1. Sem193's Avatar
    41 26-05-2012  22:57
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Doctor.)
    Right someone please help me out?

    \LARGE \int \frac{2}{x-3}


    How would I do it? :yep: I've tried looking at \LARGE \int \frac{f'(x)}{f(x)} but it doesn't really work... Pleaseeee help
    I thought it would be just 2ln(x-3)
  2. Doctor.'s Avatar
    42 26-05-2012  23:07
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    (Original post by Sem193)
    I thought it would be just 2ln(x-3)
    Exactly what I thought, but apparently its not
  3. Sem193's Avatar
    43 26-05-2012  23:59
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Doctor.)
    Exactly what I thought, but apparently its not
    That's weird. I guess I need help too.
    Last edited by Sem193; 27-05-2012 at 00:01.
  4. Doctor.'s Avatar
    44 27-05-2012  00:28
    • Vengeful, Imperial Overlord of The Student Room
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    (Original post by Sem193)
    That's weird. I guess I need help too.
    I'll have a look at that tomorrow, calling it a day now!
    Tomorrows plan is to do some other subject for the morning and end the day with C3. Is it worth doing tons of questions on 'numerical methods'? - I mean, there's only two things to it and they never change. Only iteration & sign change.

    There is a lot of questions in the C3/C4 book but Idk, what dya think I should do?
  5. king0vdarkness's Avatar
    45 27-05-2012  11:06
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    hey everyone! can anyone help me on this question \int \frac{e^{2x}}{e^{2x}+3} dx any help would be much appreciated! thanks!
  6. Doctor.'s Avatar
    46 27-05-2012  12:35
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by king0vdarkness)
    hey everyone! can anyone help me on this question \int \frac{e^{2x}}{e^{2x}+3} dx any help would be much appreciated! thanks!
    \LARGE \int \frac{e^2^x}{e^2^x+3} dx

    This has to be in the form: \huge \int \frac{f'(x)}{f(x)}dx= k ln\left |f(x) \right | + c


    So: \huge \frac{1}{2}\int \frac{2e^2^x}{e^2^x+3}= \frac{1}{2}ln(e^2^x+3)+c

    Let me know how that works out for ya
    Post rating:
    1
  7. Doctor.'s Avatar
    47 27-05-2012  12:37
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    Just finished going over Trigonometry in the book, dont' the first two pages of the misc questions. The last three questions -Too much effort Decided to just move on
  8. Doctor.'s Avatar
    48 27-05-2012  16:45
    • Vengeful, Imperial Overlord of The Student Room
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    Having trouble with the equation shown, I know how to get the values of x but the problem is what way does the \huge > sign go?

    I sort of understand which way it is when working the equation out algebraically. I want to be able to know which way the sign is supposed to go directly from the graph of the function. Is it even possible?
    I can draw it on my calculator with no problem, but when writing the solution of x, how am I supposed to know which way the > sign is supposed to be?
    \huge \left | x+2 \right |> 2x+1

    Thanks
  9. king0vdarkness's Avatar
    49 27-05-2012  22:44
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Doctor.)
    \LARGE \int \frac{e^2^x}{e^2^x+3} dx

    This has to be in the form: \huge \int \frac{f'(x)}{f(x)}dx= k ln\left |f(x) \right | + c


    So: \huge \frac{1}{2}\int \frac{2e^2^x}{e^2^x+3}= \frac{1}{2}ln(e^2^x+3)+c

    Let me know how that works out for ya
    Thanks a lot for your help... but i'm still a little confused on how you got your answer, i'm getting almost the same answer as you but it's with a 1/2e^3 ln(e^2^x+3)+c instead of 1/2 ln(e^2^x+3)+c. Could you go through all the steps of your working please thank you!
  10. Doctor.'s Avatar
    50 27-05-2012  23:07
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by king0vdarkness)
    Thanks a lot for your help... but i'm still a little confused on how you got your answer, i'm getting almost the same answer as you but it's with a 1/2e^3 ln(e^2^x+3)+c instead of 1/2 ln(e^2^x+3)+c. Could you go through all the steps of your working please thank you!
    is my answer correct? I might be wrong too!

    Right the way I did It:

    -I looked at the equation. I differentiated the bottom to see if the differential is the same as the top. It's not.
    - So I worked out what I needed to add to the top to make it equal to the differential of the bottom.
    -I put a 2 at the top. HOWEVER you cant just put a number there...So to cancel that 2 out, I put 1/2 on the outside. This means, the equation is sill the same.

    then just put it in the form of ln(...)

    that's it !
  11. king0vdarkness's Avatar
    51 29-05-2012  08:56
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Doctor.)
    is my answer correct? I might be wrong too!

    Right the way I did It:

    -I looked at the equation. I differentiated the bottom to see if the differential is the same as the top. It's not.
    - So I worked out what I needed to add to the top to make it equal to the differential of the bottom.
    -I put a 2 at the top. HOWEVER you cant just put a number there...So to cancel that 2 out, I put 1/2 on the outside. This means, the equation is sill the same.

    then just put it in the form of ln(...)

    that's it !
    Yh you're right thank you so much! You're a great help! Good luck with all your future endeavors!
  12. Doctor.'s Avatar
    52 29-05-2012  11:15
    • Vengeful, Imperial Overlord of The Student Room
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by king0vdarkness)
    Yh you're right thank you so much! You're a great help! Good luck with all your future endeavors!
    If you do need any more help, please post it up here! It really does help me learn
  13. king0vdarkness's Avatar
    53 31-05-2012  21:25
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Doctor.)
    If you do need any more help, please post it up here! It really does help me learn
    Will do!!
  14. Sem193's Avatar
    54 31-05-2012  22:36
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Doctor.)
    If you do need any more help, please post it up here! It really does help me learn
    Are you doing C4 too?
  15. Doctor.'s Avatar
    55 31-05-2012  22:52
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    (Original post by Sem193)
    Are you doing C4 too?
    (Original post by Sem193)
    Are you doing C4 too?
    I am, yeah there Is another thread somewhere for C4 too!
  16. Luppy021's Avatar
    56 01-06-2012  21:14
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    Bricking it for this exam, managed to just scrape a B overall for AS maths inc a U in stats really need a B overall!!! what are the grade boundaries like for a B? And I havent even started past papers yet... Gotta learn it all first
  17. taylore's Avatar
    57 02-06-2012  12:41
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    please may someone help with 8iii?
    really confused myself!
    thank you!
    http://pdf.ocr.org.uk/download/pp_10..._gce_4723.pdf?
  18. 710's Avatar
    58 02-06-2012  12:55
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    How are you guys feeling ahead of this, then????
  19. Doctor.'s Avatar
    59 02-06-2012  13:00
    • Vengeful, Imperial Overlord of The Student Room
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    (Original post by 710)
    How are you guys feeling ahead of this, then????
    Not all that good really I need to do more work on it tbh
  20. Doctor.'s Avatar
    60 02-06-2012  22:42
    • Vengeful, Imperial Overlord of The Student Room
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    Hey folks, I'll be doing C3 tomorrow, got a whole stack of questions sorted.

    So ill post stuff in here if I need help!
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