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# Edexcel C3,C4 June 2013 Thread watch

1. (Original post by kuku2013)
I can do them trust me just tell me which ones. its takes me an hour each paper but might leave all the easy questions
But make sure you do some of the easy qs, just so that you've practised them a bit. Sorry I haven't actually done any Solomon papers But the AEA or something like that are meant to be hard.
2. (Original post by otrivine)
but then why in the book gives

sin5x+sinx = 2sin3xcos2x

where did sin5x come from
factor formula
3. Proof of (y = a^x) in post #4711
4. Oh boy.. This one is tricky to explain because I can't speak.

You need the formula for a cone first. (1/3)(pi)(r2)h
5. (Original post by otrivine)
but then why in the book gives

sin5x+sinx = 2sin3xcos2x

where did sin5x come from
sin (3x + 2x) = sin 5x
sin (3x - 2x) = sin x

so you get sin5x + sinx
6. guys i heard paper leaked is that true?
7. (Original post by Fortitude)
But make sure you do some of the easy qs, just so that you've practised them a bit. Sorry I haven't actually done any Solomon papers But the AEA or something like that are meant to be hard.
thanks will look it up
8. Regarding formulas of shapes, do we need to know the volumes of cylinders, spheres or cones or would they give it to us in the question?
9. (Original post by Story)
Right, if instead of long division you can use the alternative comparing coefficient method first right? and then use it again to find the values or use the sub in method like you said.
You still have to do long division to get rid of the top heavy fraction, even if it is the same power! If it is the same power you can apparently split it up as partial fractions straight away but only if you do it as 3, so if it's (x+1)(x+2) on the denominator then your partial fractions would be A/(x+1) + B/(x+2) + C/(x+1)(x+2). That's according to justinawe, I've never done them that way. If you don't do them that way then you have to do long division, but that way is just for when the numerator has the same highest power as the denominator
10. (Original post by Tikara)
Awesome thanks very much mate
No problem
11. (Original post by Fortitude)
sin (3x + 2x) = sin 5x
sin (3x - 2x) = sin x

so you get sin5x + sinx
I get it

and the 2sin3xcos2x comes from?

sorry
12. (Original post by Fortitude)
Regarding formulas of shapes, do we need to know the volumes of cylinders, spheres or cones or would they give it to us in the question?
They could do either.
13. (Original post by Fortitude)
Regarding formulas of shapes, do we need to know the volumes of cylinders, spheres or cones or would they give it to us in the question?
Volume of cylinder = pi*r^2*h

volume of Sphere = 4/3 * pi * r^3

volume of cone = 1/3 * pi * r^2 * h (h is vertical height)
14. (Original post by amin666)
guys i heard paper leaked is that true?
15. (Original post by amin666)
guys i heard paper leaked is that true?
yep true and it gets worse the replacement is usually 10000 times more difficult
16. (Original post by amin666)
guys i heard paper leaked is that true?
Well the one we're doing tomorrow is the replacement paper, if you want to be confirmed.
17. I think you have to recognise that it's an equilateral triangle, so all angles are 60 degrees. Then, take the radius of the cone as r, and use tan60 = h/r to get r = h/root3. We then know that the volume of a cone is 1/3 pi r^2 h, so we sub in h/root3 as r and multiply out to get 1/9 pi h^3

Part B is more conventional C4, so I'll assume you can do that bit okay?
18. This is a stupid question, but I just want to get it confirmed: If I integrate, for example, -x+2 between the limits of a and b, I pull the negative outside the integral, switch the limits, and now integrate x-2, right? The positive and negative values of the function switch around right?
19. (Original post by Zaphod77)
You still have to do long division to get rid of the top heavy fraction, even if it is the same power! If it is the same power you can apparently split it up as partial fractions straight away but only if you do it as 3, so if it's (x+1)(x+2) on the denominator then your partial fractions would be A/(x+1) + B/(x+2) + C/(x+1)(x+2). That's according to justinawe, I've never done them that way. If you don't do them that way then you have to do long division, but that way is just for when the numerator has the same highest power as the denominator
I meant using the comparing coefficient method as a alternative to long division to get rid of the top heavy fraction?
20. (Original post by Fortitude)
Regarding formulas of shapes, do we need to know the volumes of cylinders, spheres or cones or would they give it to us in the question?
Well last question I did involved a cone and they gave it

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