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# Edexcel A2 C4 Mathematics June 2016 - Official Thread watch

1. I want to help people but at the same time I don't want to increase grade boundaries
2. (Original post by michael242103)
wait so can you write it in both ways and its correct?????
No - the ln3x one isn't correct. That is why it seems strange to be able to choose what something integrates to - you can't.

Edit: see posts below. It seems that either is fine.
3. what is the general formula for integrating a constant to a power of x (b^x)
4. (Original post by xMillnsy)
what is the general formula for integrating a constant to a power of x (b^x)
5. (Original post by SeanFM)
sean are you an actual level student or are you at uni or something ?
6. (Original post by fefssdf)
sean are you an actual level student or are you at uni or something ?
Finished 2 out of 4 years of a maths degree.
7. (Original post by SeanFM)
No - the ln3x one isn't correct. That is why it seems strange to be able to choose what something integrates to - you can't.
Both lnx /3 +C and ln3x /3 +C are correct. Using log laws, ln3x = ln3 + lnx
ln3 is an arbritrary constant. With integration, you're adding an arbritrary constant C anyway, so both answers are correct, but would have different constants.
8. (Original post by Yua)
I want to help people but at the same time I don't want to increase grade boundaries
Haha true. the number of students on this thread to the number who will not put any work in and pull the grade boundaries down will still be very high, don't worry
9. (Original post by SeanFM)
Finished 2 out of 4 years of a maths degree.
where are you studying ?
10. Hey guys, I'm a little confused here, and am probably doing something stupid:

why isn't (4ln2)² = 5ln2?

This is my reasoning:

4ln2 = ln2^4

therefore (4ln2)(4ln2) = ln(2^4) * ln(2^4) = ln(2^4 + 2^4) = ln32 = ln2^5 = 5ln2

Surely? But my calculator says otherwise. What am I doing wrong? Thanks.
11. (Original post by bossie)
Both lnx /3 +C and ln3x /3 +C are correct. Using log laws, ln3x = ln3 + lnx
ln3 is an arbritrary constant. With integration, you're adding an arbritrary constant C anyway, so both answers are correct, but would have different constants.
I stand corrected. (read: I am a pillock)
12. (Original post by Lewi348)
Haha true. the number of students on this thread to the number who will not put any work in and pull the grade boundaries down will still be very high, don't worry
im not sure about that, the grade boundaries seem to always be high no matter what for maths - last years paper was pretty hard and it was 62 for an A :/ there's too many people doing further maths these days and it just screws everyone else in terms of boundaries
13. You see how normally if you had (3x)^2 you would answer it by doing 3 to the power of root 2 and x to the power of 2. So the answer would be 9x^2

This you do the same. You square 4 whiich is 16 and ln2 squared will be simply (ln2)^2. The mistake u made was adding the numbers. The answer should be 16(ln2)^2

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14. Hard papers? I've done all the edexcel gold, June 2015 and June 2013. Any more hard ones?
15. (Original post by Polyrogue)
Hey guys, I'm a little confused here, and am probably doing something stupid:

why isn't (4ln2)² = 5ln2?

This is my reasoning:

4ln2 = ln2^4

therefore (4ln2)(4ln2) = ln(2^4) * ln(2^4) = ln(2^4 + 2^4) = ln32 = ln2^5 = 5ln2

Surely? But my calculator says otherwise. What am I doing wrong? Thanks.
you're getting the product rule mixed up.

This part here is incorrect ln(2^4) * ln(2^4) = ln(2^4 + 2^4)

The rule goes ln(a) + ln(b) = ln(ab)

It is not true for the general case that ln(a) * ln(b) = ln(a+b)
16. I've got a question.
If one does not simplify their answer, or write in surd form, or even pi form as is given in some markschemes, do I lose marks for this?
17. (Original post by Student403)
you're getting the product rule mixed up.

This part here is incorrect ln(2^4) * ln(2^4) = ln(2^4 + 2^4)

The rule goes ln(a) + ln(b) = ln(ab)

It is not true for the general case that ln(a) * ln(b) = ln(a+b)
Aha, of course. Thanks for pointing out my idiocy haha. I knew I'd done something stupid. Thanks again.
18. Hi guys I made this Core 4 Mock Paper (questions from books and the internet). You can have a go at it and I'll upload the answers in an hour. Enjoy
Attached Files
19. Core 4 Mock Paper.docx (375.7 KB, 73 views)
20. Core 4 Mock Paper.docx (410.7 KB, 82 views)
21. Core 4 Mock Paper.docx (390.9 KB, 57 views)
22. Please could someone explain b) to me from last years paper???

Attachment 555387555389
Attached Images

23. (Original post by mrt1997)
Please could someone explain b) to me from last years paper???

Attachment 555387555389
Need to work out the volume of the shape rotated. Integrate between 0 and x value of P.
Subtract from that the volume of the cone, whose height is difference between x values of P and Q, and whose radius is y value of P

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