Year 12s: what will be the first way you research your future options? >>

Edexcel C3,C4 June 2013 Thread

Scroll to see replies

Econ1994

Does anyone have the solomon papers on them? I don't understand question 7c from E and question 3b from L - would really appreciate help on how to do them, think they're tricky!

Reply 4461

justinawe

Original post by Mathletic

Would you consider that to be a harder integrand? It doesnt seem clear that thats how ts is done.

Thanks :smile:

I think it would be pretty standard, though I'm not 100% sure about that.

You could also easily integrate it using a substitution like u=x+1, btw.

(edited 10 years ago)

Reply 4462

fayled

Original post by Mathletic

Would you consider that to be a harder integrand? It doesnt seem clear that thats how ts is done.

Thanks :smile:

Personally that seems a bit of a weird method to me (well, perfectly valid, but a bit harder to spot). I would just go for algebraic long division.

Reply 4463

suncake

Original post by justinawe

\dfrac{x}{x+1}

= \dfrac{x+1-1}{x+1}

= \dfrac{x+1}{x+1} - \dfrac{1}{x+1}

= 1 - \dfrac{1}{x+1}

\therefore \displaystyle \int \dfrac{x}{x+1} \ dx = \int \left( 1 - \dfrac{1}{x+1} \right) dx = x - \ln (x+1) + C

That partial fractions/division method is beautiful. I have no idea why we don't get taught it that way, it's so much faster than long division!

Posted from TSR Mobile

Reply 4464

nm786

Original post by TDL

Anyone have the paper for this?

Paper: http://www.thestudentroom.co.uk/attachment.php?attachmentid=218600&d=1369299971

(edited 10 years ago)

Reply 4465

Kreayshawn

Original post by wndms

Can anyone please help me with this c4?
Fir part c) I know you have to equate dy/dx to 0. But then what do you do after? The answer is supposed to be (pi,-1). I don't understand .. thanks!

Posted from TSR Mobile

what paper is this from?

Reply 4466

lefterispower

Original post by jokersaurus

I have no idea how to answer any vector questions but I should be okay at getting 70 UMS+ as long as they only ask 1 vector question. Have any past papers asked more than 1 vector question?

Yes only one question per paper...but i have to tell you that vector questions based on many marks...for example last year was 14 marks...!!so you have to study them... :redface:

Reply 4467

Aikta_S

Does anyone have a really straight forward method of integration by substitution? Really panicking for tomorrow :frown:

Posted from TSR Mobile

Reply 4468

leo99756

Original post by Econ1994

Does anyone have the solomon papers on them? I don't understand question 7c from E and question 3b from L - would really appreciate help on how to do them, think they're tricky!

For 3b, think of the formulae for sin(a+b).

Sin(3x+x) = sin3xcosx + cos3xsinx
Sin(3x-x) = sin3xcosx - cos3xsinx

so sin(3x+x) + sin(3x-x) = 2sin3xcosx

Hence 1/2(sin4x +sin2x) is what you integrate. A similar method can be used on other questions with the formula for cos(a+b) as well :smile:

Reply 4469

ChemicalBond

Good luck everyone! (: Hope this one is millions of times better than C3. No words can describe how awful C3 was, so let's hope for a nice(r) C4!

Reply 4470

Lollypop95

Original post by jokersaurus

I have no idea how to answer any vector questions but I should be okay at getting 70 UMS+ as long as they only ask 1 vector question. Have any past papers asked more than 1 vector question?

june 2012

Reply 4471

SortYourLife

One thing I struggle with is vectors and finding the shortest distance, for example part d of this:

ImageUploadedByStudent Room1371482624.331712.jpg

ImageUploadedByStudent Room1371482624.331712.jpg

Any help appreciated :smile:

Posted from TSR Mobile

Reply 4472

Zaphod77

Original post by Aikta_S

Does anyone have a really straight forward method of integration by substitution? Really panicking for tomorrow :frown:

Posted from TSR Mobile

Think of it in steps: (1) Let u=a function of x (or whatever the letters are). (2) Differentiate to find dx. (3) Sub in u where appropriate and replace the dx with whatever you found after differentiating u. (4) If there are limits, find out what values of u correspond to the values of x and replace them on the integral. Hope this helped :smile:

Reply 4473

justinawe

Original post by suncake

That partial fractions/division method is beautiful. I have no idea why we don't get taught it that way, it's so much faster than long division!

Posted from TSR Mobile

I never really bother with long division, unless it's absolutely necessary. There will almost always be an alternative method anyway. Synthetic division is a lot faster and easier for me.

Reply 4474

Zaphod77

Original post by SortYourLife

One thing I struggle with is vectors and finding the shortest distance, for example part d of this:

ImageUploadedByStudent Room1371482624.331712.jpg

Any help appreciated :smile:

Posted from TSR Mobile

The shortest distance will always be the line drawn that's perpendicular between the 2 lines. This means the dot product will be 0. Draw it out - sometimes you can use triangle theorems, like when a right-angled triangle is formed :smile:

(edited 10 years ago)

Reply 4475

SortYourLife

Original post by Zaphod77

Ah right cheers :smile:

will have a go it now :biggrin:

Posted from TSR Mobile

Reply 4476

vengeance111

Original post by fayled

How can you give up revising if you never started?

Ok ive done 2 past papers, and couldnt do any of them even with text book, exam soultions tutorials mark schems
so i give up

(edited 10 years ago)

Reply 4477

Zzzyax

6. A circular cylinder has a perpendicular height equal to the radius of the base r cm.
Given that the volume of this cylinder is V cm^3

(a) show that V = (pi)r^3

Reply 4478

fayled

Original post by Zzzyax

6. A circular cylinder has a perpendicular height equal to the radius of the base r cm.
Given that the volume of this cylinder is V cm^3

(a) show that V = (pi)r^3

V=pir^2h

h=r

so V=pir^3

Reply 4479

nm786