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# Edexcel C3 (20/06) Revision Thread watch

1. Post any qs here

Also, (thanks to samdavyson for poining it out) check out the new spec (pg.29):

http://www.edexcel.org.uk/VirtualCon...cification.pdf

few things highlighted from the spec,

'At least one question on the paper will require the use of proof'

and it says ' A knowledge of the specification for C1 and C2, their preambles, prerequisites and associated formulae, is assumed and may be tested '

Edexcel Practice papers: http://intranet.millhill.org.uk/cgi/...0000000MMW&V=0
Specimen Paper: http://www.edexcel.org.uk/VirtualCon...r_MkScheme.pdf
Mock Paper:http://www.mrhughes.net/files/papers/C3/mock.pdf

Summary Sheet: http://153rd.com/sam/AS/summarysheets/C3Sum.gif
2. Not necessarily proving a formula or identity, though, right?

It might just be, like, prove some fractions equal such and such.
3. It says , methods of proof, including proof by contradiction and disproof by counter-example are required. =|
4. Do we have to know how to prove anything in particular?

For example, in C2 we had to know how to prove the arithmetic and geometric series formulas, etc.
5. From what it says, anything from C1/C2 could come up.
6. I doubt they'll go out of their way to cover something which is completely irrelevant to C3 like sequences and series. I have a suspicion it'll be something like using the laws of logarithms and then having to draw a graph.
7. This question was posted by someone else as a P2 problem, but it's within the C3 syllabus, I'm sure. There were some answers but I'm wondering if there's an easier method.

http://www.thestudentroom.co.uk/t122667.html

Please post responses in here as well, as this is the C3 revision thread!

Sin3x = cosx
8. I am so not looking forward to C3.
9. Have any of u done the specimin paper. Some of it takes the piss. The solomons were easier than the specimin. Look at question 3b in the specimin, whats that all about.
10. dus that mean in C4 we mite have sum c1 2 3 in it?
11. 1 + sinx - cosx = 1 + sin(0.5x + 0.5x) -cos(0.5x + 0.5x)

= 1 + 2sin0.5xcos0.5x - cos²0.5x + sin²0.5x

= 2sin0.5xcos0.5x + sin²0.5x + 1 - cos²0.5x

= 2sin0.5xcos0.5x + 2sin²0.5x

= 2sin0.5x(sin0.5x + cos0.5x)

EDIT: This is 3b from the C3 specimen paper.
12. (Original post by mackin boi)
dus that mean in C4 we mite have sum c1 2 3 in it?
Yes. It'll be stuff like a binomial expansion question with a positive exponent that is greater than 1 (C2)

Or having to use trig identities before you can integrate (C3)
13. (Original post by seankhn)
1 + sinx - cosx = 1 + sin(0.5x + 0.5x) -cos(0.5x + 0.5x)

= 1 + 2sin0.5xcos0.5x - cos²0.5x + sin²0.5x

= 2sin0.5xcos0.5x + sin²0.5x + 1 - cos²0.5x

= 2sin0.5xcos0.5x + 2sin²0.5x

= 2sin0.5x(sin0.5x + cos0.5x)

EDIT: This is 3b from the C3 specimen paper.

i think htat should have been worth more marks, if i remember it was ony 3 marks. but it wasnt too bad
i think htat should have been worth more marks, if i remember it was ony 3 marks. but it wasnt too bad
A specimen paper will only ever be used for revision, so if anything they'd make it harder than the real thing, I like to think. This is the first C3 paper ever as well, so we might get lucky.
15. Yeah in C4 they always have trapezium rule and thats from C2
16. (Original post by seankhn)
1 + sinx - cosx = 1 + sin(0.5x + 0.5x) -cos(0.5x + 0.5x)

= 1 + 2sin0.5xcos0.5x - cos²0.5x + sin²0.5x

= 2sin0.5xcos0.5x + sin²0.5x + 1 - cos²0.5x

= 2sin0.5xcos0.5x + 2sin²0.5x

= 2sin0.5x(sin0.5x + cos0.5x)

EDIT: This is 3b from the C3 specimen paper.
thanks
17. (Original post by sb1986)
thanks
No problem.

Anyone had a go at that sin3x = cosx question yet? The interval is 0 to 360°
18. f(x) = x+In2x-4

xn+1=4-In2xn , with x0=2.4

a.) Show your values of x1, x2, x3

Can someone show me how they put the numbers into the formula, my mind is just blank and I can't get the right answer, I'm just doing something careless.
19. (Original post by Slice'N'Dice)
f(x) = x+In2x-4

xn+1=4-In2xn , with x0=2.4

a.) Show your values of x1, x2, x3

Can someone show me how they put the numbers into the formula, my mind is just blank and I can't get the right answer, I'm just doing something careless.
x1 = 4-ln2x0

x2 = 4-ln2x1

x3 = 4-ln2x2

Is that what you mean?
20. (Original post by seankhn)
x1 = 4-ln2x0

x2 = 4-ln2x1

x3 = 4-ln2x2

Is that what you mean?
Yeah, what does these bits refer to though?

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