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# Edexcel A2 C4 Mathematics June 2015 - Official Thread watch

1. i remember that day i tried solomon...
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never looked at another solomon paper again! Those things make me feel like i havent learnt anything yet the questions that come up in edexcel papers are straightforward. If anything solomon papers are a waste of time! (This is just my opinion). I know some people who did solomon A-Z or whatever it ends at and still found the C3 paper "damn hard". On the other hand GOLD papers are legit edexcel papers and they stick to the point and don't make you think outside the outside of the box!
2. (Original post by Paraphilos)
Note that ; then, see my post above.

If you meant a square on then I really don't think you guys have learnt this, surely?

We've had to differentiate similar terms with the x squared, so I was wondering how to integrate them I've tried the method you proposed but it just becomes really messy when I try and substitute back in
3. (Original post by kdevitto)
Thankyou!
no problem, hope it helps!
4. (Original post by humayra.ac)
only 2 marks :| anybody ?
5/8ln(4x^2+1)
5. (Original post by Ripper Phoenix)
i remember that day i tried solomon...
Spoiler:
Show
never looked at another solomon paper again! Those things make me feel like i havent learnt anything yet the questions that come up in edexcel papers are straightforward. If anything solomon papers are a waste of time! (This is just my opinion). I know some people who did solomon A-Z or whatever it ends at and still found the C3 paper "damn hard". On the other hand GOLD papers are legit edexcel papers and they stick to the point and don't make you think outside the outside of the box!
Should start doing solomon at the very start of you're revision and learn from them, then once you've done solomons the real papers are so straight forward.
6. (Original post by jmuz)
Hi sorry can u elaborate a little bit more
Ok, so you want to solve:

We make the substitution, . Then we can write: . Substitution into yields:

which, upon the inversion back to a function of means that:

7. (Original post by jubilant_joej)
Cheers! So if it's got say x^4 on top and x^2 on bottom, it can be done as Ax^2 + Bx + C + D/denominators
yeah exactly! basically if the highest power on the numerator is the same as or higher that the highest power on the denominator you have to do the algebraic long division (or whatever method you use to divide the equation) to find the A B and C etc, then the remainder becomes the top of the fraction as D
8. (Original post by joe1545)
Should start doing solomon at the very start of you're revision and learn from them, then once you've done solomons the real papers are so straight forward.
I guess it varies from person to person. I have always done all edexcel, then GOLD. Its just the best way for me
9. (Original post by Paraphilos)
Ok, so you want to solve:

We make the substitution, . Then we can write: . Substitution into yields:

which, upon the inversion back to a function of means that:

thank you so much
10. (Original post by Paraphilos)
Note that ; then, see my post above.

If you meant a square on then I really don't think you guys have learnt this, surely?
is there a reason you didn't square the 5 also? Or am i missing something :/
11. (Original post by H1143999)
We've had to differentiate similar terms with the x squared, so I was wondering how to integrate them I've tried the method you proposed but it just becomes really messy when I try and substitute back in
I can understand you having to differentiate them, but having to integrate them relies on the method of substitution; the conditions of this require the integrand to have a term that corresponds to the derivative of some part of the function you wish to integrate (in this case a derivative linearly dependent on ). The reasons of this are beyond A level, but basically it's because the method requires you to have that derivative in the integrand as a result of FTC.

In short, I don't think you will be asked it unless you have an term in the integrand.
12. (Original post by humayra.ac)
only 2 marks :| anybody ?
5/8 ln(4x^2 +1)

It's by recognition that f'(x)/ f(x) is integrated to lnf(x). You just need to manipulate the numerator for it resemble f'(x). In this question f'(x) would = 8x which is why you need to multiply by 5/8.
13. (Original post by DalvirSingh)
is there a reason you didn't square the 5 also? Or am i missing something :/
It's according to the rules of exponentiation; note that, .

14. Sorry if this is a stupid question, but is there a reason why you can't integrate this by expanding the brackets and then using IBP on -xe^2x? The mark scheme doesn't offer it as an option, plus I tried it and it came out wrong (although that could've been down to me making a mistake)
15. (Original post by joe1545)
Split the variables, and rearrange, this bits probably the longest part of the question, but you should then get.

2Sin2yCosy dy = ex dx

Now let U = SinY

du/dy = Cosy

du = Cosy dy (which is coincidentally the last bit of the equation)

So the equation now becomes 2u2 du

Integrate with respect to U to get 2/3U3 sub U back in and we get 2/3Sin3Y = ex + c
thank you so much!
16. (Original post by themorninglight)

Sorry if this is a stupid question, but is there a reason why you can't integrate this by expanding the brackets and then using IBP on -xe^2x? The mark scheme doesn't offer it as an option, plus I tried it and it came out wrong (although that could've been down to me making a mistake)
What method do they use?
17. (Original post by themorninglight)

Sorry if this is a stupid question, but is there a reason why you can't integrate this by expanding the brackets and then using IBP on -xe^2x? The mark scheme doesn't offer it as an option, plus I tried it and it came out wrong (although that could've been down to me making a mistake)
which paper is that from?
18. (Original post by themorninglight)

Sorry if this is a stupid question, but is there a reason why you can't integrate this by expanding the brackets and then using IBP on -xe^2x? The mark scheme doesn't offer it as an option, plus I tried it and it came out wrong (although that could've been down to me making a mistake)
what paper is this ?
19. (Original post by Paraphilos)
Ok, so you want to solve:

We make the substitution, . Then we can write: . Substitution into yields:

which, upon the inversion back to a function of means that:

sorry one more thing,

is that a rule that could be applied to any equation in that form e.g

integrating

3^2u (wrt u) would therefore equal… 3^2u / 2ln3
20. when do you know to take a constant outside of a function before you integrate??

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