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

1. (Original post by KINGYusuf)
Guys you know if d2y/dx2 is > 0 it's a MINIMUM

d2y/dx2 < 0 it's a MAXIMUM

If d2y/dx2 = 0 is it point of inflection? What do you do next 3rd differential or something idk? How can you make sure
You wouldn't do anything after that except for if you have time at the end then run through the question again
2. Guys when do I need to change from degrees to radians mode on my calc? HELP
3. (Original post by Haych97)
Just come across this question on an IAL, have no idea how to do it and not sure if its part of our spec
12x= 1 x nx
x's cancel therefore nb=12
4. (Original post by Haych97)
The question attached

Hope you understand this :P Because a circle is 2pi and if you divide a circle into 6 little triangles, you get the angle pi/3
5. (Original post by sharp018)
Guys when do I need to change from degrees to radians mode on my calc? HELP
misread the question: Most of the time area of a sector, area/ length. They would probably want you to use sin/cosine in radians too.

Also sometimes in trig identities
6. Soo confused?

in some question the geometric sequence power r has been subtracted by minus 1 in other question it remains unchanged.
how do we know when to subtract 1 or leave r with no power?
7. (Original post by .JC.)
Which paper?
Someone on this thread linked it so I tried to attempt it and got nowhere

http://qualifications.pearson.com/co...-June-2014.pdf
8. Guys what year is the hardest maths paper?

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9. (Original post by frozo123)
yeah just use the 1 + nx ting
Care to elaborate?
10. (Original post by sharp018)
Guys when do I need to change from degrees to radians mode on my calc? HELP
Whenever the question is to do with sectors and area of triangles. Also for some trig equations, it will state the interval in which would imply whether you use radians or degree.
11. (Original post by frozo123)
12x= 1 x nx
x's cancel therefore nb=12
part b
12. (Original post by Haych97)
Someone on this thread linked it so I tried to attempt it and got nowhere

http://qualifications.pearson.com/co...-June-2014.pdf
Don't think that's anything to do with our spec.
13. (Original post by frozo123)
If d2y/dx^2 is 0, if you differentiate it again and does not equal 0, then it's a point of inflexion
& if in the 3rd differential is 0? Then it's inconclusive?
14. (Original post by .JC.)
Care to elaborate?
Its called equating co-effiecients

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15. (Original post by .JC.)
Care to elaborate?
in the formula booklet there are two formulae for binomial expansions

one is in the form ( 1 +x)^n
where the first number has to be 1
so if I had (3+6x)^ 4
I would have to do first of all ( 3(1+2x) ) ^4 then 81 (1 +2x)^4
then you just follow the formula
it's easier than the nCr crap
16. (Original post by jtlmao)
Guys what year is the hardest maths paper?

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January 2010 its only 54 to get an A
17. (Original post by mrchemistry)
Do you guys think we would be expected to know formulas for 3d shapes? E.g. cylinder, cone, sphere, etc?
I pretty certain it will come up and I hope it does. It's really easy and worth a lot of marks.
18. but if I'm using the equation for example when the angle given is in radians and I want to find the arc length, so the formula is theta x r, do I still need to switch to radians mode?

(Original post by kkboyk)
Whenever the question is to do with sectors and area of triangles. Also for some trig equations, it will state the interval in which would imply whether you use radians or degree.
19. (Original post by sharp018)
Guys when do I need to change from degrees to radians mode on my calc? HELP
Whenever you see superscript c / rad - usually this is for angles in triangles or circle questions

Also if you're asked to solve for x in a sin/cos/tan question with ...pi<x<...pi you'll need to use radians.
20. (Original post by sharp018)
but if I'm using the equation for example when the angle given is in radians and I want to find the arc length, so the formula is theta x r, do I still need to switch to radians mode?
Yes thats the whole point

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