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

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Reply 40
Original post by Doctor.
Right someone please help me out?

2x3\LARGE \int \frac{2}{x-3}


How would I do it? :yep: I've tried looking at f(x)f(x)\LARGE \int \frac{f'(x)}{f(x)} but it doesn't really work... :tongue: Pleaseeee help :smile:


I thought it would be just 2ln(x-3)
Reply 41
Original post by Sem193
I thought it would be just 2ln(x-3)


Exactly what I thought, but apparently its not :angry:
Reply 42
Original post by Doctor.
Exactly what I thought, but apparently its not :angry:


That's weird. I guess I need help too.
(edited 11 years ago)
Reply 43
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! :colonhash:
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? :tongue:
hey everyone! can anyone help me on this question e2xe2x+3dx\int \frac{e^{2x}}{e^{2x}+3} dx any help would be much appreciated! thanks! :smile:
Reply 45
Original post by king0vdarkness
hey everyone! can anyone help me on this question e2xe2x+3dx\int \frac{e^{2x}}{e^{2x}+3} dx any help would be much appreciated! thanks! :smile:


Unparseable latex formula:

\LARGE \int \frac{e^2^x}{e^2^x+3} dx



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


So:
Unparseable latex formula:

\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 :h:
Reply 46
Just finished going over Trigonometry in the book, dont' the first two pages of the misc questions. The last three questions -Too much effort :tongue: Decided to just move on :h:
Reply 47
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?
x+2>2x+1\huge \left | x+2 \right |> 2x+1

Thanks :h:
Original post by Doctor.
Unparseable latex formula:

\LARGE \int \frac{e^2^x}{e^2^x+3} dx



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


So:
Unparseable latex formula:

\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 :h:


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! :smile:
Reply 49
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! :smile:


is my answer correct? I might be wrong too! :tongue:

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(...) :smile:

that's it !
Original post by Doctor.
is my answer correct? I might be wrong too! :tongue:

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(...) :smile:

that's it !


Yh you're right thank you so much! You're a great help! Good luck with all your future endeavors! :wink:
Reply 51
Original post by king0vdarkness
Yh you're right thank you so much! You're a great help! Good luck with all your future endeavors! :wink:


If you do need any more help, please post it up here! It really does help me learn :h:
Original post by Doctor.
If you do need any more help, please post it up here! It really does help me learn :h:


Will do!! :biggrin:
Reply 53
Original post by Doctor.
If you do need any more help, please post it up here! It really does help me learn :h:


Are you doing C4 too?
Reply 54
Original post by Sem193
Are you doing C4 too?


Original post by Sem193
Are you doing C4 too?


I am, yeah :smile: there Is another thread somewhere for C4 too!
Reply 55
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 :frown:
Reply 56
please may someone help with 8iii?
really confused myself!
thank you!
http://pdf.ocr.org.uk/download/pp_10_jan/ocr_52277_pp_10_jan_gce_4723.pdf?
Reply 57
How are you guys feeling ahead of this, then????
Reply 58
Original post by 710
How are you guys feeling ahead of this, then????


Not all that good really :frown: I need to do more work on it tbh
Reply 59
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! :smile:

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