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# Edexcel A2 C4 Mathematics June 2015 - Official Thread Watch

1. Pls help!! Really worried because I got the signs wrong for this question so would I at least get 1/3 for writing 32(In2)^2
2. Pls help!! Really worried because I got the signs wrong for this question so would I at least get 1/3 for writing 32(In2)^2.
3. (Original post by smem_96)
For question 8b you'd probably get 2/3 method marks, just none of the answer marks
4. (Original post by jayjay531)
I'm not sure, because 4000 isn't the right number so you might lose mark for that, and then you couldn't get an answer if you used 4000 - (I know this because I didn't read the question either at first and only when I kept getting math error on my calculator I then realised I was supposed to be using 4). So to answer your question, I don't really know how many marks you'd get for that.
5. (Original post by 11234)
Pls help!! Really worried because I got the signs wrong for this question so would I at least get 1/3 for writing 32(In2)^2.
Anyone?
6. could 71/72 be 100ums
7. Someone please help!! The only mistake I made was somehow calculating k as 2 for question 6...how many marks would I lose? Does follow through even count?

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8. (Original post by smem_96)
I'm not sure, because 4000 isn't the right number so you might lose mark for that, and then you couldn't get an answer if you used 4000 - (I know this because I didn't read the question either at first and only when I kept getting math error on my calculator I then realised I was supposed to be using 4). So to answer your question, I don't really know how many marks you'd get for that.
Thank you!
9. [QUOTE=xKay;57135357]Have you had a look at the jan 13 exam?[/QUO

Yeh ,just now
10. (Original post by hasan6091)
This is really not fair, i have double checked the spec and looked through 3 text books and it does not state anywhere that you have to integrate 3^x or anything similar. So i was never taught it and never came across it in exams.
Im going to loose six marks because of it
You are expected to know how to integrate by substitution, and how to differentiate 3^x. It was perfectly fair of Edexcel to set this question,
11. (Original post by anorris13)
You are expected to know how to integrate by substitution, and how to differentiate 3^x. It was perfectly fair of Edexcel to set this question,
Even if i used subsitution i would not be able to do the question because of the fact that i do not know how to integrate a constant raised to a power because its not in any book or in the spec so my teachers didnt bother teaching it
12. 67-68 in C3 63-64 in C4
A*????
13. (Original post by V0ldemort17)

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You might lose a method mark and then the final answer mark, so long as the rest of your working is correct
14. (Original post by hasan6091)
Even if i used subsitution i would not be able to do the question because of the fact that i do not know how to integrate a constant raised to a power because its not in any book or in the spec so my teachers didnt bother teaching it
I think you are missing the point.... the whole reason to use a substitution is to integrate something that you cannot otherwise integrate

if you let u=3^x, du/dx=3^xln3 which is equivalent to uln3. Therefore dx=(1/uln3)du.
Change the limits and sub in and you end up having to integrate u wrt u. I believe this is in the specification.
15. (Original post by Abzey_97)
67-68 in C3 63-64 in C4
A*????
Possibly but marginal. Likely 95 UMS for C3, and probably 84/85 for C4, but nobody can really say when it is this close.
16. (Original post by anorris13)
I think you are missing the point.... the whole reason to use a substitution is to integrate something that you cannot otherwise integrate

if you let u=3^x, du/dx=3^xln3 which is equivalent to uln3. Therefore dx=(1/uln3)du.
Change the limits and sub in and you end up having to integrate u wrt u. I believe this is in the specification.
When you put it that way you are correct i was using the wrong subsitution.
What grade do you think 48-57 would be
17. (Original post by anorris13)
Possibly but marginal. Likely 95 UMS for C3, and probably 84/85 for C4, but nobody can really say when it is this close.
thanks
18. (Original post by hasan6091)
When you put it that way you are correct i was using the wrong subsitution.
What grade do you think 48-57 would be
I think 57 will be about 75 UMS, 48 maybe 60ish, not really very good at predicting these beyond the 90 UMS area
19. (Original post by Abzey_97)
thanks
No worries, don't stress on it. Do you need an A* for uni?
20. (Original post by anorris13)
No worries, don't stress on it. Do you need an A* for uni?
nope, its more of a personal ambition and something that I feel is not beyond my reach.
I need an ABB for physics, maths and chem. in any order.

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