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# Mr M's OCR (not OCR MEI) Core 2 Answers May 2013 Watch

1. Howdy again.

Looking over 9ii), I think my long division goofed up (or somehow I did the worst factorisation known to man), and I ended up with (2x+1)(2x+3)(x-1). I'd obviously lose out on some accuracy marks, but would the fact I factorised and did long division mean I'd still be in the running for most of the method marks?

Also, that'd mean my answer to 9iii) was fundamentally incorrect. But would the fact (if I did it right) I managed to convert those figures into angles and apply them on a CAST diagram net me a couple of marks?

Thanks.
2. (Original post by Expert #7451)
Howdy again.

Looking over 9ii), I think my long division goofed up (or somehow I did the worst factorisation known to man), and I ended up with (2x+1)(2x+3)(x-1). I'd obviously lose out on some accuracy marks, but would the fact I factorised and did long division mean I'd still be in the running for most of the method marks?

Also, that'd mean my answer to 9iii) was fundamentally incorrect. But would the fact (if I did it right) I managed to convert those figures into angles and apply them on a CAST diagram net me a couple of marks?

Thanks.
Yes. I think you will get 4 marks for 9ii) and 3 marks for 9iii)
3. For 7.ii i got the equation of the tangent right but i integrated it wron but my method was still correct after that.
For 8.iii i got to the point of x=2/(log2(a)-log2(b))
How many marks would i get on each?
4. (Original post by Mr M)
That's the correct method. The C2 specification states that knowledge of C1 may be required. This continues at A2 - C4 assumes knowledge of C1, C2 and C3.
wish I knew that, I did the same but forgot how to differentiate so did dy/dx= then decreased power and divided by the power do you think I will get any marks? I continuined to calculate the area under the graph by doing graph minus triangle??

also for logs I did:
a^x=4b^x
xlog2 a=log2 4+xlog2 4b
x log2 a = 2 + xlog2 4b times all by a -.-
x log 2 aa - x log2 4ab= 2
then I can't remember it went downhill but I did somehow end up with th log. how many marks can I expect?
5. (Original post by DutchyBoy)
For 7.ii i got the equation of the tangent right but i integrated it wron but my method was still correct after that.
For 8.iii i got to the point of x=2/(log2(a)-log2(b))
How many marks would i get on each?
7ii) get 3 or 4 marks

8ii) get 2 marks
6. (Original post by BenChard)
wish I knew that, I did the same but forgot how to differentiate so did dy/dx= then decreased power and divided by the power do you think I will get any marks? I continuined to calculate the area under the graph by doing graph minus triangle??

also for logs I did:
a^x=4b^x
xlog2 a=log2 4+xlog2 4b
x log2 a = 2 + xlog2 4b times all by a -.-
x log 2 aa - x log2 4ab= 2
then I can't remember it went downhill but I did somehow end up with th log. how many marks can I expect?
I expect you will get 2 marks for 7ii), one for attempting to differentiate and one for subtracting the triangular area.

Looks like 2 marks for the logs.
7. (Original post by Mr M)
I expect you will get 2 marks for 7ii), one for attempting to differentiate and one for subtracting the triangular area.

Looks like 2 marks for the logs.
thanks. I think I've lost 9+/-1, would that be an a or is it borderline? thanks
8. (Original post by BenChard)
thanks. I think I've lost 9+/-1, would that be an a or is it borderline? thanks
I think the grade boundaries will be quite high, but you should be okay with 61/62. But it would be a low A.

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9. (Original post by Namige)
I think the grade boundaries will be quite high, but you should be okay with 61/62. But it would be a low A.

Posted from TSR Mobile
thanks, can only hope now!
10. Mr M, on 7ii) I differentiated the tangent then found the equation of the line then made it =0 and then got confused with the integration as I integrates between 5/3 and 1, how many marks would I have dropped out of the 5?
11. (Original post by BenChard)
thanks. I think I've lost 9+/-1, would that be an a or is it borderline? thanks
12. (Original post by science-oliver)
Mr M, on 7ii) I differentiated the tangent then found the equation of the line then made it =0 and then got confused with the integration as I integrates between 5/3 and 1, how many marks would I have dropped out of the 5?
Well that is potentially all correct. Are you saying you made a mistake with your integration? If so, lose 1 or 2 marks.
13. How do you solve the last question?? I couldn't even begin it to find even one value of x. I wrote down 3 correct answers for x through complete guesses at the end but no working, will i get any marks?
14. (Original post by Mr M)
Well that is potentially all correct. Are you saying you made a mistake with your integration? If so, lose 1 or 2 marks.
I thought the part where I integrated between 5/3 and 1 was wrong as I integrated between 5/3 which was right, but integrated with the wrong limit? As I didn't think you were to integrate with x=1?
15. (Original post by science-oliver)
I thought the part where I integrated between 5/3 and 1 was wrong as I integrated between 5/3 which was right, but integrated with the wrong limit? As I didn't think you were to integrate with x=1?
Oh I see. Yes the 1 limit is incorrect. Lose 2 marks I expect.
16. (Original post by ZCYZSRIW)
How do you solve the last question?? I couldn't even begin it to find even one value of x. I wrote down 3 correct answers for x through complete guesses at the end but no working, will i get any marks?
You were supposed to make the connection between part (iii) and part (ii) (you needed to make the substitution ).

Correct answers in an exact form with no extra answers will gain full marks. The examiner will just assume you solved it in your head (this is perfectly possible if you know what you are doing).
17. (Original post by Mr M)
Oh I see. Yes the 1 limit is incorrect. Lose 2 marks I expect.
thank you!
18. For the last question with the logs, I had all of the logs with x on 1 side and factorised X out leaving the logs in the brackets without showing the log law loga^b = blog(a) is that okay???

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19. (Original post by smithstefan1995)
For the last question with the logs, I had all of the logs with x on 1 side and factorised X out leaving the logs in the brackets without showing the log law loga^b = blog(a) is that okay???
I have no idea what you are describing. Could you type that step out?
20. Hi Mr M
on the first question I made the most ridiculous mistake and put 3 instead of 2 as H
I worked out all the Y values and wrote out the formula correctly (obviously with 3 instead of 2 though)
how many marks do you think I will lose?

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