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# Edexcel C2 20th May 2015 *Official Thread* watch

1. (Original post by Pikki1234)
How many marks would I lose if I wrote 4cos^2x-4cosx =k instead of factorising it?

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i got that too i was so confused how were u supposed to factorise?
2. (Original post by ezrad)
162??????????
That's what I got but it's wrong I'm afraid. There was a negative area, but that's theoretical negative, because it's an area you have to make it positive making the final answer 234 or whatever people are saying
3. (Original post by target21859)
For the question where you had to express cosx in terms of k, did you get 4cos^2x-cosx-k=0?
Not sure if what I did was right but something like (1+- root 1+16k)/8
4. fairly standard paper in all honesty, bit of revision and the job gets done
5. (Original post by TheAstrocist)
Maybe, I can't remember exactly what he said
it was 162
6. (Original post by 12345678zzz)
dC/dr and just substitute r into it
should have found r = 2.92 (3 s.f.)

integrate both sections using the curve, should either did 192+34 or 162+64
Omg......
I skipped the geometric series question as I really didn't like it at all. I didn't mind losing those marks if I did everything else.
I got to the last question with only a few minutes left, so didn't bother with part a) and attempted part b).
I think I differentiated the equation correctly, then cancelled out pi and then divided by 12r, to leave me 1/25= r^-3

My mind went completely blank and all this logarithm stuff just came to mind because of the amount of crap on the paper to do with it.
I didn't realise that I should of just cube rooted 25, to get 2.92 (3 to the nearest pound).

This paper was awful and totally unfair of the number of hard questions in the time given. A-level maths should be difficult and challenging, but exam papers need to be reasonable. 2014 and 2013 was a lot easier and doable in the time limit.

Basically dropped 20 marks right away from missed questions and known wrong answers, can't wait to find what else I got wrong.
7. (Original post by gabbons)
224 ?
I remember something along the lines of 30+194.
But our values are that close it probably doesn't matter
It was 32

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8. (Original post by hasnain123)
i got (3x-12)(x+4) why is that wrong ? someone help meh pls
I got the same but I think you had to simplify 3x-12 you will only lose 1 mark, if that
9. (Original post by hasnain123)
i got (3x-12)(x+4) why is that wrong ? someone help meh pls
Which question?
10. Pretty good test, climb up the ladder if you want another go, otherwise come over to the monitors to be debreifed
11. (Original post by eyeman567)
Yes thats what I got lol
I think that was the right answer...
12. (Original post by Ukranium)
4cos^2x - cosx -3 = 0

(4cosx +3 )(cosx - 1)

x = cos^-1 ( -3/4)
x = cos^-1(1)

you only put the solutions for x=cos^-1(-3/4)

what about the solutions of cos^-1(1)???
Oh, that is what i got, put 0 degrees too, but not in my final answer, it was sorta seperate, i was going to put 360 too but realised the range

So, yeh, i think that is what i got

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13. (Original post by 1asdfghjkl1)
i got that too i was so confused how were u supposed to factorise?
Quadratic equation bruv

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14. i see ERRRRRRRRR
(Original post by Columbo97)
That's what I got but it's wrong I'm afraid. There was a negative area, but that's theoretical negative, because it's an area you have to make it positive making the final answer 234 or whatever people are saying
15. Had to rearrange for cosx in terms of k:
cosx = (1+Root(1^2 + 16k))/8
16. (Original post by TheAstrocist)
one hundred and something, I think 226 is right, but you never know
I got 162, maybe he thought it was that??
17. That paper was worse than a solomon paper omg
18. i really messed up that paper
19. (Original post by 1asdfghjkl1)
i got that too i was so confused how were u supposed to factorise?
I put that too, what was the question?

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