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Edexcel C4 June 2009 Thread :)

Amz_1

no lol but nearly they are on either side of the radius kind of thing wait actually u could do it ur way too

basically they act as radiuses as they have to cut the circle at two places

imagine a line intersecting the circle

so ur triangle dont work :| lol

C IS THE CENTRE!!!!

oh yeah, i see. it's one of rules we learnt in C2 right, about the radius cutting on a chord (whatever its called)? But yeah, thanks.

Reply 181

Amz_1

4

lazyman987

oh yeah, i see. it's one of rules we learnt in C2 right, about the radius cutting on a chord (whatever its called)? But yeah, thanks.

YUP YOUVE GOT IT!! :smile:

Reply 182

Waterstorm

16

T Taila

awesome, thanks :]
and i came accross this question, i dnt really need help in it, but wow its a bitch im so confused :

∫2x^2sec^2xtanx dx

intergrate that by parts... wtf?

Only thing I can think of doing is letting

u = 2x^2

and putting dv/dx as the rest, and integrating that but interpretation, so using the reverse of the chain rule. Try letting

y = sec^2x

, and see what you get.

Reply 183

Sapphire Rose

This thread is depressing me...

I thought I was alright with C4 but clearly not :sad:

Reply 184

Waterstorm

16

milan5baros

How Can I integrate this

\int10cosx(sinx)^4\ dx

is there any quicker ways than parts?

By interpretation, reverse of the chain rule.

Let

y = sin^5x

, you'll get the answer nice and quickly and needing just a few steps.

Reply 185

T Taila

to be honest, i tried tons of ****, its just too hard, oh well, i doubt somthin like that will pop up in the exam, fingaz crossed :smile:

thnx tho

Reply 186

logic123

the answer for thast is 5sinx^5x

Reply 187

xRachelx

hey people, good luck in your C4 exam!
im stuck on cartesian equations!! how do you work them out??

send an example lol

Making the non x/y (usually t) letter the subject then putting x back into y, for parametric equations that is. Not sure how it's done for Vector questions.

Reply 190

Char56

1

kinglrb

Can some please explain this to me? C4 is driving me mad.

u= 2^x

How on earth is du/dx= 2^x multiplied by ln2?

y=a^xlna

They may ask you to prove this and apply it to a question like you asked...it was on a solomon paper, highly unlikely they would put it on a normal edexcel paper but it's better safe than sorry!

Let y=a^x

Take logs of both sides...

lny = xlna

Rearrange and differentiate...

(1/y) dy/dx = lna

dy/dx = ylna

Sub y back in...

dy/dx = a^xlna

Hope that helps too!

Reply 191

R£SP£CT

15

twinkle9

i totally agree!!! from C1-C3 found maths ok, now i've just completely lost my confidence :s-smilie:

, i hope they lower the grade boundaries!!!! im so scared for this exam :frown:

been revising but i dont think i've got anywhere lol :eek3:

same here! :frown:

stupid edexcel!. They better lower the grade boundaries! I tried the solomon papers and now im in the same position your in. Totally lost my confidence :frown:

.
But i think they might go easy on us this year ^_^ given that the previous papers were solid. However that said, they might give us an impossible paper lol.

2 days away!!! urghhh stupid Vectors and integration!! Theyre driving me crazy!

Heres a quick tip for your exam. When you arrive at college for your exam and you are seated, quickly with a pencil write down all the formulas and things you know on the paper, so you dont have to remember them when doing the exam! ^-^

Reply 192

kinglrb

12

I am really screwed I don't know whats gone wrong. I was fine two weeks ago but since I've been doing other exams and revision it seems all of my c4 knowledge has disappeared. I am struggling with every single question, I am really panicking, haven't got a clue what to keep doing to improve my chancesof getting a decent grade.

Reply 193

R£SP£CT

15

Char56

y=a^xlna

They may ask you to prove this and apply it to a question like you asked...it was on a solomon paper, highly unlikely they would put it on a normal edexcel paper but it's better safe than sorry!

Let y=a^x

Take logs of both sides...

lny = xlna

Rearrange and differentiate...

(1/y) dy/dx = lna

dy/dx = ylna

Sub y back in...

dy/dx = a^xlna

Hope that helps too!

Yep thats correct. I remember doing the solomon papers and it came up. 2 marks for that question, and all that working out!!! damn them!

Reply 194

R£SP£CT

15

kinglrb

I am really screwed I don't know whats gone wrong. I was fine two weeks ago but since I've been doing other exams and revision it seems all of my c4 knowledge has disappeared. I am struggling with every single question, I am really panicking, haven't got a clue what to keep doing to improve my chancesof getting a decent grade.

I was in the exactly same position 2 days ago and its not pleasent. Just make sure you know your stuff. Practice integration, its the main theme of C4. Remember some of the questions can involve you using identities from C3 and stuff from other modules. Go through recent papers with the markscheme and it should preferably help you remember some of the stuff. Take it easy and relax, dont overstress yourself, otherwise it will just lead to a breakdown.

p.s. if you need anything just let us know.

Reply 195

kinglrb

12

R£SP£CT

I was in the exactly same position 2 days ago and its not pleasent. Just make sure you know your stuff. Practice integration, its the main theme of C4. Remember some of the questions can involve you using identities from C3 and stuff from other modules. Go through recent papers with the markscheme and it should preferably help you remember some of the stuff. Take it easy and relax, dont overstress yourself, otherwise it will just lead to a breakdown.

p.s. if you need anything just let us know.

Thanks man, I am on the verge of breaking down, I feel so unprepared and this test will literally make or break my uni offer so stress levels are like sky high.

Thanks for the help though I really appreciate it.

Reply 196

twinkle9

R£SP£CT

same here! :frown:

stupid edexcel!. They better lower the grade boundaries! I tried the solomon papers and now im in the same position your in. Totally lost my confidence :frown:

.
But i think they might go easy on us this year ^_^ given that the previous papers were solid. However that said, they might give us an impossible paper lol.

2 days away!!! urghhh stupid Vectors and integration!! Theyre driving me crazy!

Heres a quick tip for your exam. When you arrive at college for your exam and you are seated, quickly with a pencil write down all the formulas and things you know on the paper, so you dont have to remember them when doing the exam! ^-^

aww thanx, great tip!!!! will be doing that lol, exam tomorrow!!!! so nervous!!!!! :s-smilie:

and don't worry R£SP£CT u'll do great!!!!

Reply 197

Char56

1

I thought they gave us alright papers for C3, M1 and M2...so they may possibly do the same with C4 tomorrow =)

Quick question...How do I go about this one?

Integrate sin3xcosx dx

I used parts and the mark scheme used parts and substitution...and it's only a four mark question! Is there a slicker way than this?
Thanks!

dsafa

Char56

I thought they gave us alright papers for C3, M1 and M2...so they may possibly do the same with C4 tomorrow =)

Quick question...How do I go about this one?

Integrate sin3xcosx dx

I used parts and the mark scheme used parts and substitution...and it's only a four mark question! Is there a slicker way than this?
Thanks!

I think you could use this identity

\displaystyle \sin A - \sin B \equiv 2\cos \left(\frac{A+B}{2}\right)\sin \left(\frac{A-B}{2}\right)

Edexcel C4 June 2009 Thread :)

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