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# Edexcel A2 C4 Mathematics June 2015 - Official Thread watch

1. Guys, what'd you think is more helpful at this point? Soloman papers or gold paper?
( i've done a couple of each but not all)

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2. (Original post by MrBowcat)
Was that IAL?
yup
3. Wouldn't mind a really nasty differential equation question, but a really nice vectors question.
4. (Original post by joe1545)
Wouldn't mind a really nasty differential equation question, but a really nice vectors question.
ditto
5. (Original post by FKA Stiglitz)
When you have your binomial expansion in the form (1+ax)^n, it's valid for mod x < 1/a; for example a=2 so 2x, it's valid for mod x < 1/2.
thanks bruh
6. Anyone else dreading this exam tomorrow? im feeling confident!! but i did for C3 then opened the paper haha
7. Guys how do you know which value to make u for substitution? I get confused.. or can you just use any of the two vlues e.g sin x cos^3 x
I would have made cos^3 x to (cosx)^3 and then cosx= u but on the mark scheme they make sin x = u.
Why?
8. How do you this is it a standard pattern type ? thank
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9. (Original post by Phenylethanone)
how do you know when to use the normal formula for volume of revolution OR the one whens it a parametric curve?
usually u know it when they say it was turned 2pi or something like that most times they say the word revolution in the question
10. Kmttt keep makin these likkle errors like forgetting to put the minus sign and i drop a lot of marks

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11. https://5a302d29ff432793ce79475dd3db...%20Edexcel.pdf
how do you do question 2?
12. When doing integration by substitution, you know you have E.g. X=2u & you then find dx/du=2, from this point on do you have a way of knowing whether of not you:

flip that to get dx/du=1/2 and then just write at the end of your integral: 1/2du as then the two du's cancel, or from dx/du=2 should multiply both sides by du to get dx=2du ?

Hope that made sense

I've always done it the first way but Im not sure if im right
13. (Original post by humayra.ac)
How do you this is it a standard pattern type ? thank
Yeah but i got stuck on this and asked my teacher and she said its not in the edexcel syllabus anymore so don't worry about it
14. (Original post by manlikem)
Guys how do you know which value to make u for substitution? I get confused.. or can you just use any of the two vlues e.g sin x cos^3 x
I would have made cos^3 x to (cosx)^3 and then cosx= u but on the mark scheme they make sin x = u.
Why?
I thought if you were to use substitution, it gave you the substitute?
15. oh really thanks

(Original post by katie*may)
Yeah but i got stuck on this and asked my teacher and she said its not in the edexcel syllabus anymore so don't worry about it
16. apply the a^x rule where if you differentiate a^X you get a^xlna

17. (Original post by Alice Moody)
I thought if you were to use substitution, it gave you the substitute?
what do you mean? The question is just integrate sinx cos^3 x dx
18. (Original post by humayra.ac)
apply the a^x rule where if you differentiate a^X you get a^xlna
that's what I was thinking but what you do with the 16? may you go through it
19. Does anyone know when you put the modulus bars wrapped around a function in- is it just when you integrate? And whether or not you can lose marks for putting in brackets instead?
20. (Original post by manlikem)
what do you mean? The question is just integrate sinx cos^3 x dx
oh....sorry thought the first bit was saying about using a substitute

sorry

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