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# OCR (not MEI) Core 3 - 19/01/2011 watch

1. is mr M going to give the answers?
2. (Original post by Revolution is my Name)
There are two potential ways of finding alpha, one involving inverse tan of 7/24 (by dividing the two expressions involving alpha), the other inverse sin of 7/25 (by using the R value found), both of which give the same alpha value
That's it. I thought I ended up inversing 7/24 not 7/25! That's put me so much at ease, thank you!
3. Hardest paper ever!
My first choice uni want an A in C3 so unless they lower the boundary to like 40/72, definately looks like a retake. Fml
4. (Original post by JackWoot)
Ahhhhh why didn't I recognise (ln(x))^2 + 8 as a chain rule question?

Ahhh no facepalm can take away the shame I'm feeling after doing that exam.
Really? Crap.

Initially I went for 2lnx (LoL). Didn't like that. Went for........... lnxlnx +8 => 1/x times 1/x => 1/x^2 !
5. (Original post by Glen_Nichols)
45000
What did you get for question 9?
6. (Original post by yourworstnightmare)
When there's a modulus sign: |-3a| = +3a
so we didn't have to work out what a was?

should the answers just be x=a/3 and x=3a
7. Wow, it's active in here.

The Rsin(theta + a) question,

did everyone get R=25 and a=16.3?
8. (Original post by Princess_perfect786)
the retake in june is not going to be any easier, is it?
Aww, don't cry!

Trust me, I wanted to cry last January too. But I waited until results day and I was really shocked! I actually brought in my money to pay for a resit and scored >90%.

For an error as small as that, you will get full marks minus 1, so chin up

As for Jan vs June; the June paper for 2010 was considered harder but it was probably because there was a 10 mark question where you had to differentiate, then integrate and then work out an area, it put many people off, tbh it sort of shook me for a minute or two when I had a look at it.

Apart from that, the Jan paper was probably harder. Looking on the brightside, if you HAVE to resit, well now you'll have had a feel for the exam, timings, questions, and you'll be more familiar with the exam structure and your technique will be better and with C4 knowledge, you'll have such a broad knowledge of Mathematics that you may even perform a lot better.

The very best of luck to you and do PM anytime if you require any help or just want a chat about the exams/problems, any exam board, any subject

9. (Original post by nikita_atikin)
Wow, it's active in here.

The Rsin(theta + a) question,

did everyone get R=25 and a=16.3?
R is certainly 25.

a is whatever sin-1(7/25) is, I don't have a calculator, sorry
10. (Original post by Just_looking_for_help)
I hope who ever created this paper burns in hell -_- It was barely anything like all the past papers... T.T
My teacher reckons that there's been a new chief examiner since Jan 2010's paper. And he's been adapting each paper from the old ones to his style, so Junes going to be just as bad, if not worse :/
11. Did anyone else get 149/3 for a on the 9 mark question?
12. in question 2, would the graph intersect the y axis at 4 or -4?
13. (Original post by Princess_perfect786)
so we didn't have to work out what a was?

should the answers just be x=a/3 and x=3a
Yep, when it says 'solve' it's generally for x, unless stated otherwise

The a was just a number to sort of confuse/challenge you and your thinking.

If the a was a 6 or any integer, i'm sure many candidates wouldn't have had a problem, but because it was a letter, it becomes a little more tricky and fiddles with your mind.

I've been through it, trust me
14. (Original post by Sophie.atlanta)
Hardest paper ever!
My first choice uni want an A in C3 so unless they lower the boundary to like 40/72, definately looks like a retake. Fml
15. (Original post by nikita_atikin)
Wow, it's active in here.

The Rsin(theta + a) question,

did everyone get R=25 and a=16.3?
yes!

not that i won't be retaking anyway. i must have got something like 15/72
16. If anyone's interested, I think I got the following (I think! I'm also not claiming to be a Mr M!):

1) x=(1/3)a or x=-3a
2) Stationary point at (-5,24) - translate -3 units parallel to x-axis, stretch s.f. 4, reflect in x-axis.
3) 45000cm^2 h^-1 (2sf)
4) i)25sin(theta + 16.3)
ii)12.4, 135
5) a=9, Vol. = 24*pi*ln5
6) i)dy/dx=(-6x^3 + 32x +6)/((x^3 - 4x^2 +2)^2), then show that...
ii) (2.398, -1.552)
7) i) Sq. root (e^8 - 8)
ii) f has inverse : e^x
iii) 6/e^3 (or 6e^-3)
iv) 20.3
8) ai) Drawing y=cosecx
aii) beta = 3*pi - alpha
bi) tan(2x) = 2tanx/(1-(tanx)^2)
bii) 225/322
9) i) Show that... comes out to be sum of two positive exponentials
ii) Show that... I made f"(x) = 4f(x). Then x>0.25ln3
iii) g(x) > or equal to 2*(sq root k)
17. (Original post by yourworstnightmare)
R is certainly 25.

a is whatever sin-1(7/25) is, I don't have a calculator, sorry
You did your exam without a calculator?
18. (Original post by Glen_Nichols)
Really? Crap.

Initially I went for 2lnx (LoL). Didn't like that. Went for........... lnxlnx +8 => 1/x times 1/x => 1/x^2 !
Yeah I did something similar lnxlnx +8 => 1/x * ln(x) = ln(x)/x

Apparently it was 2ln(x)/x so I wasn't too far off.
19. (Original post by jayjay1)
is mr M going to give the answers?
He's a Mathematics teacher so when he gets home, settles down, has his meal/normal family related stuff, i'm sure he'll be generous enough to give up some time to solve the paper.

I believe the FP1 paper was also sat on OCR today so he may have to look around in both threads, just be patient, he'll be here when he's got time
20. (Original post by Princess_perfect786)
in question 2, would the graph intersect the y axis at 4 or -4?
The cosec graph doesn't intersect the Y axis, it's an asymtote

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