x Turn on thread page Beta
 You are Here: Home >< Maths

# Official Edexcel C3 Discussion Thread watch

1. (Original post by Arsey)
Cot 2x can equal zero; look at the graph of cot x. It gives 2 extra solutions, 45, 135 which ARE valid in the original equation. I know it is confusing but it has been explained it detail earlier. If you didn't include them you've lost 2 marks.
would you mind clarifying my previous question, because i have used incorrect working to get cot2x=1 i will lose most of the marks even though i got 2 correct solutions
2. no your method is wrong but incredibly lucky. You will just get the accuracy marks for the final answers.
3. (Original post by aper_son)
http://www.wolframalpha.com/input/?i=Ln|x|

Yes it does thanks a lot...
i'm happy I got it right

How did you find the paper??
4. (Original post by Arsey)
33 I think
It may not be the same for everyone because of browser settings; some people may have it set so that there are a certain number of posts per page.
5. Did any1 attempt q8 using the Rcos(4x+alpha) method???
6. (Original post by crazedmonkey09)
you reckon i will lose a mark for leaving it as 4/(3x+3)(3x+1)
I did the same. Hopefully it will be fine.
7. quick question:

if a lot of people messed up the January paper, there are bound to be lower grade boundaries, so when we do get our results, will they be the results after edexcel has set all their boundaries and made allowances?!
if so, then what's the point of re-taking the exam in June?

i'm sorry i'm just very confused with this whole concept
9. When differentiating does anyone else just go straight into it, rather than showing

u=
u'=
v=
v'=

Will it be ok?
10. im pretty sure you dont need to 'sshow' those and can just go straight into it
11. (Original post by Xtian)
When differentiating does anyone else just go straight into it, rather than showing

u=
u'=
v=
v'=

Will it be ok?
Ye im sure u dont need to show it if ur answers right, but useful for method marks if answers wrong...
12. What do people think the boundries will be?
13. (Original post by tqpbuildingbonds)
for ques 8 i don't completely agree with the unofficial mark scheme...i think it's:
cot2x = 0 => tan2x = 0
2x = arctan0
= 0, 180
so x = 0, 90
and NOT 45, 135 (As stated in the unofficial MS)

correct me if i'm wrong plz...
lol i did that too at first, then when I went back to check it, I changed it to the cot2x = 0 and got 45, 135

For once in my life, I checked through the paper and actually changed something to save me a few marks
14. (Original post by zomgleh)
quick question:

if a lot of people messed up the January paper, there are bound to be lower grade boundaries, so when we do get our results, will they be the results after edexcel has set all their boundaries and made allowances?!
if so, then what's the point of re-taking the exam in June?

i'm sorry i'm just very confused with this whole concept
Ok if everyone does badly then the grade boundaries will be lowered...

However if you did so badly that even after the grade boundaries are lowered then you are still below average score then you still get a bad grade ...

If that's the case you should retake in June to get a better grade.

Reasonably simple concept but if you need explaining some mroe i'll have another attempt in a second.
15. 55-60/75 for an A
16. (Original post by lmfao)
What do people think the boundries will be?
i think A will be in this range 54-57
17. (Original post by john1234567)
meh i guess. i just recognised that is the derivative of arctanx, which is what the question is getting us to find, so i was just lucky i suppose although i don't think it would've confused me even if i hadn't known that lol
I have no idea what the derivative of arctanx is but still managed to do that question and I'm usually the kind of person who often misread ans makes such silly mistakes.. so it can't have been THAT badly worded..?
18. http://www.wolframalpha.com/input/?i...%5E2%29%29%2B3

judge for yourself if it is fg(x) >=3
19. last year I did c2 . One question got 4 answers but I got only 2, still have 100%
In this c3 exam i got only 3 answers for the cot2x question by stupid mistake T___T Can i still have 100% ?
20. (Original post by Catherine91)
But that could also be written as:

1/tan2x = 0

...meaning tan2x couldn't = 0 ?
I think u have to look at the graph of cotx. I did it so many times, my teacher confirmed that, trust me
So when cot2x=0 2x= 90/ 270
but i excluded 270 by mistake

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: June 14, 2010
Today on TSR

### I've studied the wrong subject

...Should I go back to school?

### Should I complain about my supervisor?

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