You are Here: Home >< Maths

# Edexcel C3,C4 June 2013 Thread watch

1. (Original post by Better)
Dan helped me on the second part.

To solve an Equation. You can either.
1. Equate and Solve Algebraically. You will then get your solution.
2. Draw the graph for the both and see where the intersect. Intersection point is the solution.

Hence they drew a graph

The other bit I can't remember but Post a link so other people can see it.
I get it! They manipulated f(x) = 0 to get two equal graphs. Ahh.
2. Does anyone know how to work out Q8c on the C3 Solomon Paper A?
3. (Original post by sounique)
Does anyone know how to work out Q8c on the C3 Solomon Paper A?
The root is where the lines intersect...

x^2 + 1 = 1/x-2

(x-2)(x^2+1)-1=0

x^3 - 2x^2 + x - 3 = 0

f(x) = x^3 - 2x^2 + x - 3

Test out a few integers... when the sign changes, you know to start of with one of the 2 integers then do the usual process....
4. Hey guys, can someone help me please

Integration by parts question from the edexcel book... Answer is meant to be -xcotx + ln(sinx) + C. Where have I gone wrong?

Posted from TSR Mobile
5. (Original post by posthumus)
The root is where the lines intersect...

x^2 + 1 = 1/x-2

(x-2)(x^2+1)-1=0

x^3 - 2x^2 + x - 3 = 0

f(x) = x^3 - 2x^2 + x - 3

Test out a few integers... when the sign changes, you know to start of with one of the 2 integers then do the usual process....
Thanks! So, can we literally choose any integers for x0, and then sub into the iterative formula and we should get the same answer?
6. (Original post by sounique)
Thanks! So, can we literally choose any integers for x0, and then sub into the iterative formula and we should get the same answer?
I would have thought so yes... I just checked the mark scheme and they used Xo= 3 , although personally I would have thought 2 would be better since it gave answer closer to 0 (sorry if I ruined any surprises). but it does say "e.g."
7. (Original post by suncake)
Hey guys, can someone help me please

Integration by parts question from the edexcel book... Answer is meant to be -xcotx + ln(sinx) + C. Where have I gone wrong?

Posted from TSR Mobile
I think when you integrated sin(x)^-2 you never used the reverse chain rule.
for example if v = -cosecx then dv/dx = cosecxcotx not (sinx)^-2
8. (Original post by suncake)
Hey guys, can someone help me please

Integration by parts question from the edexcel book... Answer is meant to be -xcotx + ln(sinx) + C. Where have I gone wrong?

Posted from TSR Mobile
This is how I would work it out.
Attached Images

9. (Original post by posthumus)
I would have thought so yes... I just checked the mark scheme and they used Xo= 3 , although personally I would have thought 2 would be better since it gave answer closer to 0 (sorry if I ruined any surprises). but it does say "e.g."
I did notice the e.g, I just assumed there was something lying deeper than that, something I didn't yet fully understand. Thanks mate
10. (Original post by suncake)
Hey guys, can someone help me please

Integration by parts question from the edexcel book... Answer is meant to be -xcotx + ln(sinx) + C. Where have I gone wrong?

Posted from TSR Mobile
third line - you integrated wrong, you need to use: since
11. (Original post by sounique)
This is how I would work it out.
Yeah I realised that way was easier afterwards Thanks!

(Original post by nmanvi)
I think when you integrated sin(x)^-2 you never used the reverse chain rule.
for example if v = -cosecx then dv/dx = cosecxcotx not (sinx)^-2
How would you reverse chain rule sinx^-2 when it's just a single x? I don't get what you mean

(Original post by gaffer dean)
third line - you integrated wrong, you need to use the identities since:
Oh I see haha. Thanks!

(This is what happens when you neglect maths for a whole two weeks )

Posted from TSR Mobile
12. (Original post by suncake)
Yeah I realised that way was easier afterwards Thanks!

How would you reverse chain rule sinx^-2 when it's just a single x? I don't get what you mean

Oh I see haha. Thanks!

(This is what happens when you neglect maths for a whole two weeks )

Posted from TSR Mobile
ignore me hun was chatting nonsense
13. Can someone please explain where they got the 3 pi /2 on Q7 in the C3 Solomon C Paper. Shouldn't they equate it to pi where the minimum occurs?
14. c4 solomon paper aren't to different to the normal exam papers
15. (Original post by yaboy)
c4 solomon paper aren't to different to the normal exam papers
I agree, I haven't really seen any big difference between the two myself...
16. just came across a very odd question in the c3 solomon C on question 4d. have no idea why they used OD
17. (Original post by yaboy)
just came across a very odd question in the c3 solomon C on question 4d. have no idea why they used OD
Umm, does the following diagram explain what they did? Basically AB is the base of the triangle, OD is the height, they've used the standard way of calculating modulus then used the basic triangle area formula (1/2 x base x height).

Let me know if you want a more detailed solution
18. (Original post by Lilmzbest)

Umm, does the following diagram explain what they did? Basically AB is the base of the triangle, OD is the height, they've used the standard way of calculating modulus then used the basic triangle area formula (1/2 x base x height).

Let me know if you want a more detailed solution
but that would only work if D is the midpoint of A and B and I dont know how you would know that.
19. Came across an unfamiliar question earlier from the Edexcel C3 January 2007 paper: question 8ii. The question is on inverse trigonometric functions (arcsin x, arcos x, arctan x), and whilst it isn't hugely difficult once you see the method, the second part was only answered correctly by 10% of candidates according to the examiner's report (I think this is simply due to unfamiliarity - it's one of those areas of the spec which doesn't appear very often in the exam.) It's covered briefly in the blue and green Edexcel C3 textbook but the examples given aren't that helpful. A useful source of help is the "PatrickJMT" Youtube account: http://www.youtube.com/user/patrickJMT?feature=watch
20. (Original post by Vistaprint)
Came across an unfamiliar question earlier from the Edexcel C3 January 2007 paper: question 8ii. The question is on inverse trigonometric functions (arcsin x, arcos x, arctan x), and whilst it isn't hugely difficult once you see the method, the second part was only answered correctly by 10% of candidates according to the examiner's report (I think this is simply due to unfamiliarity - it's one of those areas of the spec which doesn't appear very often in the exam.) It's covered briefly in the blue and green Edexcel C3 textbook but the examples given aren't that helpful. A useful source of help is the "PatrickJMT" Youtube account: http://www.youtube.com/user/patrickJMT?feature=watch
that video left me knowing no more on how to do that question than before I watched it. which was nothing

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: September 24, 2013
Today on TSR

### Exam Jam 2018

Join thousands of students this half term

### Solo - A Star Wars Story

Poll
Useful resources

Can you help? Study help unanswered threadsStudy Help rules and posting guidelinesLaTex guide for writing equations on TSR

## Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE