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# Edexcel C2 20th May 2015 *Official Thread* watch

1. (Original post by rachelw785)
I am struggling with parts of C2, especially with the differentiation parts and finding the maximum and minimum points etc., can anyone tell me how they remember how to do this? I have no idea
To Differentiate: multiplying the coefficient of x by the power, and then the power minus one.
To find the max and minimum points; make the gradient (the first differentiation or dy/dx) equal 0. Use this to find x

Hope this helps, sorry if its unclear..
2. (Original post by Olon)
what the query
3. Just some formulas which are not on the formula sheet & the proof of the first n terms in a geometric sequence just in case anyone needs it.
Attached Images
4. C2.pdf (107.8 KB, 183 views)
5. i dont know how i got a D last year but right now im feeling so confident. does anyone have any other question for this paper i can do since i went through all the past papers?
6. When can you use ncr on calculator and when do u have to use n! /r! (n-r)!
7. Are there any exam questions, where you have to change the log bases?

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Attached Images

9. (Original post by frozo123)
what the query
https://c4a3f001dcd45afe69d0ceec8300...%20Edexcel.pdf

Q6
Q8c,d,e
10. (Original post by Alevel2015.)
When can you use ncr on calculator and when do u have to use n! /r! (n-r)!
Use the second formula for binomials in the formula book, you use it again at A2 and it's a lot easier to use imo.
11. (Original post by leoben49)
Just some formulas which are not on the formula sheet & the proof of the first n terms in a geometric sequence just in case anyone needs it.
Can you print screen please, my pc doesn't seem to read the size of the file :/
12. (Original post by tevagx51)

Tevaaaaaaaaaaaaaaaaaaagxhttps://c4a3f001dcd45afe69d0ceec8300...Edexcel.pdfFor Q6) whenever they ask you if it's a diameter do you use that formula?And can you help me with: 6c, q8b and 9a

Thanks
13. (Original post by Dahir123)

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Is this a genuine question? its in degrees and the range is in radians? what?

14. Someone please help me with this question because I am completely unable to understand how to simplify
15. http://qualifications.pearson.com/co...-June-2014.pdf

16. (Original post by Alevel2015.)
When can you use ncr on calculator and when do u have to use n! /r! (n-r)!
They both do the exact same thing, nCr is just a quick calculator shortcut of writing out that formula
17. (Original post by usmanzubair)

Someone please help me with this question because I am completely unable to understand how to simplify
Multiply it out by the denominator, and then bring it to the left hand side making it equal to zero And then factorise I think
18. (Original post by usmanzubair)

Someone please help me with this question because I am completely unable to understand how to simplify
Multiply both sides by (4sin(2*theta) - 1) and you've got something you can factorise.
19. (Original post by the north)
i dont know how i got a D last year but right now im feeling so confident. does anyone have any other question for this paper i can do since i went through all the past papers?
The question attached
Attached Images

20. (Original post by usmanzubair)

Someone please help me with this question because I am completely unable to understand how to simplify
-Multiply both sides by 4sin2 theta -1

-Subtract the sin2theta from the other side giving you 3sin2theta -1=0

- Move the 1 to the other side to give 3sin2theta =1

- Divide by 3 to give sin2theta = 1/3

- Sin inverse giving 2theta =sin-1 (1/3)

- Get your 2 results, and then divide by two, giving you theta, take into consideration the range
21. (Original post by Olon)
If you could help me with these
https://c4a3f001dcd45afe69d0ceec8300...Edexcel.pdfFor Q6) whenever they ask you if it's a diameter do you use that formula?And can you help me with: 6c, q8b and 9a
Which formula?
For 6 a centre is (3, -2) and radius is 5
For 6 b you just work out the distance between P and Q by drawing (or imagining) a right angled triangle and using Pythagoras and that should be the diameter. Essentially just sqrt((- 5 - 1) ^ 2 + (7 - - 1)^2) should equal 5*2.
For 6 c if PRQ is 90 deg then R lies on the circle. You might like to draw this out if you can't see this straight away. As R is on y axis, bung x = 0 into the first equation in part a and solve.
For 8 b you can work out the constant logs on top of the equation. Then multiply everything by log2(x) and you get (log2(x))^2 = 9 and x = 2^3 and x = 2^-3
For 9a work out arc length using 2*pi*r*(angle/2pi) = r here and work out sector area using pi*r^2*(angle/2pi) = r^2/2 here and then add areas of surfaces up

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