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# Edexcel C3,C4 June 2013 Thread watch

1. (Original post by CompSci101)
Does anyone have a (link to)/(copy of) the current Edexcel A Level Mathematics Specification?
The one linked on their website currently points to a 404.
http://www.edexcel.com/migrationdocu...2%20180510.pdf
http://www.examsolutions.net/maths-r.../C4/module.php
2. What proofs do we need to know (if any)?
3. (Original post by Kreayshawn)
is there an easy way to tell if a fraction is top heavy, for when we're doing partial fractions?

usually when I look at the partial fraction I look at all its degree (or expand all the x's in my head)

ect

in my head i see the highest degree for the top being 3 and the lowest being 2 (also noticing it is in the final form - theres no further expanding)

3/2 is top heavy
4. (Original post by keromedic)
I've no idea how to draw graphs from parametric equations. Eek
We won't have to.
5. (Original post by kuku2013)
catch me up what question is this?

hi

integrating sin3xcosx dx
6. (Original post by Myocardium)
What proofs do we need to know (if any)?
y = a^x

dy/dx = a^x lna

Spoiler:
Show
y = a^x

ln y = xlna

1/y . dy/dx = ln a

dy/dx = y ln a

(From y = a^x )

Therefore: dy/dx = a^x ln a
7. All the best for tomorrow guys!!

Please remember though that discussion of this exam won't be allowed at all until midnight after the exam has taken place. This is to prevent people who haven't yet done the exam from getting an unfair advantage over you. More information here: http://www.thestudentroom.co.uk/anno...hp?f=373&a=629

Thanks, and good luck!
8. (Original post by Zaphod77)
I'll be honest, I can't think of a way... I'd just stick to sec^2(x), a lot easier! I was trying to manipulate it, but I'm not sure you can... Sorry!
Its cool, the sec^2(x) is what I will keep in mind!
9. differenitate

at(1-t) ?

use product rule?
10. Well guys, my school said today that they have put in a complaint about that atrocious C3 paper we did on Thursday because they did say it was bang out of order!
11. (Original post by usycool1)
All the best for tomorrow guys!!

Please remember though that discussion of this exam won't be allowed at all until midnight after the exam has taken place. This is to prevent people who haven't yet done the exam from getting an unfair advantage over you. More information here: http://www.thestudentroom.co.uk/anno...hp?f=373&a=629

Thanks, and good luck!
But how comes, now they have international papers, so they cant
12. Hi,
Thanks for that, however I was wondering whether there is an official one from edexcel.

For example Physics Specification would look like this: http://www.edexcel.com/migrationdocu...cs_Issue_5.pdf
13. (Original post by otrivine)
http://www.school-portal.co.uk/Group...urceId=3992069

how would you do question 3)b)

SinA + SinB = 2sin(A+B/2)cos(A-B/2)
1/2(SinA + SinB) = sin(A+B/2)cos(A-B/2)

A+B/2 = 3x
A-B/2 = x

A = 4x, B = 2x

Now integrate 0.5sin4x + 0.5sin2x
14. (Original post by Zaphod77)
A general solution is one that contains a constant, e.g. after integration when you have "+c". A particular solution is one where you've worked out what "c" is.

Look at the highest power of x on the top and bottom. If the top has a higher power, it is top heavy.
thanks you're the best ^^

but what if the degree is the same as on the bottom - I heard it was also top heavy then, so like (x^2)/(3x^2+5) is this top heavy?
15. (Original post by otrivine)
Oh sorry!

Yeah, you can do it by substitution.
16. (Original post by otrivine)
But how comes, now they have international papers, so they cant
Because Edexcel told us we need to keep the restrictions and not all international countries do a different paper.
17. (Original post by otrivine)
hi

integrating sin3xcosx dx
you use the first trigonometric identity on the C3 part of the formula booklet something like sin(A plus/minus B) = sin A cosB( plus/minus) cosA sin B
18. (Original post by kronca)
usually when I look at the partial fraction I look at all its degree (or expand all the x's in my head)

ect

in my head i see the highest degree for the top being 3 and the lowest being 2 (also noticing it is in the final form - theres no further expanding)

3/2 is top heavy
And for that type you would be A + B/(whatever) + C/(whatever) ?
19. (Original post by otrivine)
Correct, can you show me please
Ok first look at page 93, Example 6c.

1. You can see that sin3xcosx is in the addition formula sin (A+-B) = sinAcosB +- cosAsinB. A is obvs 3x & B is x.
2. So you can have sin (3x + x) = sin3xcosx + cos3xsinx
3. But you need to get sin3xcosx
4. You can also have sin (3x - x) = sin3xcosx - cos3xsinx
5. We need to get just sin3xcosx on it's own so in order to do that, you can tell that we need to add the equations: (sin3xcosx + cos3xsinx) + (sin3xcosx - cos3xsinx) so we end up with 2sin3xcosx.
6. You need to also therefore add the sin (3x+x) + sin(3x-x) so you get sin 4x + sin2x = 2sin3xcosx
7. Hence now just divide by 2 so you get 1/2(sin4x + sin2x) = sin3xcosx
8. Just integrate (sin4x + sin2x) & then x1/2 & subs limits in!!!

20. (Original post by Tikara)
thanks you're the best ^^

but what if the degree is the same as on the bottom - I heard it was also top heavy then, so like (x^2)/(3x^2+5) is this top heavy?
Yes, in that you have to divide it through before splitting into partial fractions or create 3 fractions, as justinawe showed me earlier - I tend to divide through! Doing partial fractions normally don't work on that kind of fraction

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