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# C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST Tweet

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1. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
Hey guys ive got a query you know for the range/domain question, well i stupidly put greater than or equal to 3 when it was just greater than 2.. i was just wondering you know the second one for the domain if the inverse i put the same thing down will i still get error carried forward for this mark???

much appreciated!
2. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
(Original post by joneasy)
right if you could right it as that then could you set cos3x = 0 then get an answer from that??
NO!

From your equation there are 2 solutions

1. Cos 3x = 0

or

2. Tan 3x = -3/square root 3

The correct one is the second solution which arsey used to get x. You would have had to ignore the Cos 3x =0
3. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
What do people say the grade boundaries will be realistically? i think i got 61-64 since i messed up on silly stuff -.-
many people found it a hard paper so i am hoping it will be lower than jan
many thanks
Last edited by Amirrryy; 15-06-2012 at 01:55.
4. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
Completely messed up the question about inverse functions/domain/range although I had studied that topic the most. I don't know what happens to me during exams, it's like i forget everything. I know that you're supposed to move f(x) up by 2 points and then reflect it in y=x and the inverse graph crosses the x axis at the same point where f(x) crosses the y-axis but i still put down something completely different. and for the range of f(x) i said it's y>0 although that would be true for e^x not e^x + 2 I must have not read the question properly. For the question where we had to differentiate using the quotient rule i squared 5 which was outside the bracket when really i should have just multiplied 5 by 2. I know that because I had practiced those questions so many times yet in the exam I did something else. I was rushing towards the end anyways and we were only given an hour and 25 mins, not the full hour and 30 mins. So dissapointed in how this exam went, I couldn't even finish in time.
5. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
(Original post by annony)
Hey guys ive got a query you know for the range/domain question, well i stupidly put greater than or equal to 3 when it was just greater than 2.. i was just wondering you know the second one for the domain if the inverse i put the same thing down will i still get error carried forward for this mark???

much appreciated!
i hope you do cos i made the same error! cant believe i got it wrong omg wanna shoot myself -.- i put > 0 for some reason...but i put the same thing for the domain of the inverse. Idk if we will get e.c.f marks hope we do!
6. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
elie
(Original post by Al04)
Completely messed up the question about inverse functions/domain/range although I had studied that topic the most. I don't know what happens to me during exams, it's like i forget everything. I know that you're supposed to move f(x) up by 2 points and then reflect it in y=x and the inverse graph crosses the x axis at the same point where f(x) crosses the y-axis but i still put down something completely different. and for the range of f(x) i said it's y>0 although that would be true for e^x not e^x + 2 I must have not read the question properly. For the question where we had to differentiate using the quotient rule i squared 5 which was outside the bracket when really i should have just multiplied 5 by 2. I know that because I had practiced those questions so many times yet in the exam I did something else. I was rushing towards the end anyways and we were only given an hour and 25 mins, not the full hour and 30 mins. So dissapointed in how this exam went, I couldn't even finish in time.
I thought 3 divided by root 3 or whatever = 3 -_- cost me that whole question
When working out the solutions for Rcos I drew out the cos graph to see where the solutions lie .. Instead drawing cos intersecting at 90 and.360 instead of 270 ... I've drawn a million trig graphs since year 10 and not once have I made that mistake ... And now in the C3 exam that alone cost me 5 marks... Trust me your not the only one..
7. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
(Original post by Arsey)
I thought this was a fairly standard paper but it did have lots of parts to questions that could cause a lot of problems

There hasn't been a summer session boundary of less than 60 since 2007 and I really can not see it happening this time either; my best guess at boundaries is:

75 = 100ums
69 = 90ums
63 = 80ums
56 = 70ums
49 = 60ums
42 = 50ums
35 = 40ums

Here are some links to previous D1 threads, they are worth a read and you will see what the common errors were...

C3 Jan 2012 - http://www.thestudentroom.co.uk/show....php?t=1903204

C3 June 2011 - http://www.thestudentroom.co.uk/show....php?t=1619039

The second link has loads of past papers, mark schemes, model solutions etc
hey arsey, first of all thanks for posting this. I had a couple of questions:
1) on q1 i think i got arithmetic wrong and got 2/the square brackets instead of 6. would i lose one mark or 2?
2) also on the domain range q, idk how i managed to get it wrong i put > 0 , but afterwards i put the same thing for the domain of the inverse, so would i get e.c.f marks on it?
3) on the last question, i also made an arithmetic error, q8(c) got 7cos2x - 25sin2x - 1 instead of 7 :/ but used that answer in the last part of the q and did 25 + 1 = 26 as the maximum instead of 25 + 7 so would i get e.c.f marks here also?
what about grade boundaries wise? in terms of an A, B etc?
much appreciated
Last edited by Amirrryy; 15-06-2012 at 02:30.
8. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
(Original post by shooby_doo)
elie

I thought 3 divided by root 3 or whatever = 3 -_- cost me that whole question
When working out the solutions for Rcos I drew out the cos graph to see where the solutions lie .. Instead drawing cos intersecting at 90 and.360 instead of 270 ... I've drawn a million trig graphs since year 10 and not once have I made that mistake ... And now in the C3 exam that alone cost me 5 marks... Trust me your not the only one..
Oh i made a similar mistake with the Rcos question at the end, since we were stopped early i didn't even read what part c) and d) were. -_-
But to be honest if the rest of the paper was ok for you then don't worry about those parts too much! I know i made mistakes in between as well, like i didn't know how to prove that sec^2 theta identity either. Then i made another dumb mistake when working out the y value for question 3 i think, I said that zero times 1= 1 LOL. I'm always in a rush and make mistakes when putting things into my calculator and i fail to simply read questions properly haha. I don't think I'm alone though! :/
Last edited by Al04; 15-06-2012 at 15:04.
9. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
(Original post by Amirrryy)
i hope you do cos i made the same error! cant believe i got it wrong omg wanna shoot myself -.- i put > 0 for some reason...but i put the same thing for the domain of the inverse. Idk if we will get e.c.f marks hope we do!
hahaha i put >0 too and i have no idea why! i think i was thinking of e^x rather than e^x +2. so yup we'd lose the mark for the domain of the inverse i think and possibly for the graph if we don't get the asymptotes(but I'm really not sure..). Well I know I will cause even on my graph i drew the intersection and the asymptotes according to y=e^x not y=e^x +2.
10. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
Going by this ill have 72/75
Forgot to draw the asymptotes on the f(x) f^-1(x) graph
Got the points crossing the axes right though so I'll get one out of the four
All my other answers were spot on
Poor way to lose marks but really happy with the paper overall
How'd everyone else find it?
11. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
Thank you, Arsey
12. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
Well I completely failed this exam, looking at arsey's results
13. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
which one is correct?

14. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
Hope its 69 for 90 or less.
Guys if you can pls help me i had a few question:
1.In last question part c i did it right but didnt state values of a,b,c and wrote it in 7 +7cos2x-24sin2x wont i get any mark out of 2??
2.Also in d second differentiation in 7 i showed quotient rule but working was wrong so wont i get M mark??

15. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
I did the exact same thing! I hope it's correct
16. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
You won't lose a mark for not writing the values for a,b,c, and d and I'm sure you'll get that M mark but not the A mark
17. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
(Original post by Arsey)
I thought this was a fairly standard paper but it did have lots of parts to questions that could cause a lot of problems

There hasn't been a summer session boundary of less than 60 since 2007 and I really can not see it happening this time either; my best guess at boundaries is:

75 = 100ums
69 = 90ums
63 = 80ums
56 = 70ums
49 = 60ums
42 = 50ums
35 = 40ums

Here are some links to previous D1 threads, they are worth a read and you will see what the common errors were...

C3 Jan 2012 - http://www.thestudentroom.co.uk/show....php?t=1903204

C3 June 2011 - http://www.thestudentroom.co.uk/show....php?t=1619039

The second link has loads of past papers, mark schemes, model solutions etc
hi arsey i think i got 63 raw marks on this paper, what would be the least i would get in ums mark!
18. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
(Original post by yagami018)
You won't lose a mark for not writing the values for a,b,c, and d and I'm sure you'll get that M mark but not the A mark
Ok thanks i hope u are right..but still worried abt the differentiation..
19. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
I really can't quite understand why people are getting negative reps for saying they have done well?
I think being successful is great and none of those who stated they did well did it to rub others noses in it.

In terms of the paper, I didnt think it was as hard as many past papers for the following reasons:
(1) Domain and range/functions question was not as tough as it could have been
(2) No wordy questions on trig or e/ln functions
(3) Graph transformations were very straight foward
(4) On stationary point, no requirement to find y value
(5) A fair amount of the trig gave exact values

Concerns:
(1) Algebra/Calculus required attention and quite detailed which may lead to errors
(2) Some may panic on trig identity

Overall I thought it was fairly ok after going through it post exam and feel students who needed a resit from January probably would have been happy with the paper, especially if they had not focused too heavily on C3 in favour of C4.
20. Re: C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST
For question 2(c),I took +/- 0.005 as the suitable interval instead of +/- 0.0005....will I get marks for that???

and for 7(b) how many marks will I get for only finding dx/dy
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