The Student Room Group

FP3 Limits Question

FP3 text book Q5 on page 24.

Can someone write up their working in good detail with clear steps so I can compare it with mine. Thanks
Original post by SBurn98
FP3 text book Q5 on page 24.

Can someone write up their working in good detail with clear steps so I can compare it with mine. Thanks


What exam board?
Reply 2
Original post by SBurn98
FP3 text book Q5 on page 24.

Can someone write up their working in good detail with clear steps so I can compare it with mine. Thanks


Why don't you show us your working first and provide a picture or link to the question?
Original post by SBurn98
FP3 text book Q5 on page 24.

Can someone write up their working in good detail with clear steps so I can compare it with mine. Thanks


Ok seeing as you are doing limits on p.24 I will assume you want help with

 limxx2+3xx\ \lim_{x\rightarrow \infty} \sqrt{x^2 +3x } - x

You might want to rationalize this, hope that helps.
Original post by zetamcfc
Ok seeing as you are doing limits on p.24 I will assume you want help with

 limxx2+3xx\ \lim_{x\rightarrow \infty} \sqrt{x^2 +3x } - x

You might want to rationalize this, hope that helps.


Isn't that already rationalised? I'd try a Taylor series approach.
Original post by atsruser
Isn't that already rationalised? I'd try a Taylor series approach.

Spoiler

Original post by zetamcfc

Spoiler



Right. I knew what you meant, but I was just questioning your terminology - I think that you are irrationalising it :smile: (actually rational/irrational don't make sense here really, but that's by the by.)

Why don't AQA like Taylor series? Surely any correct method is acceptable?
Original post by atsruser
Right. I knew what you meant, but I was just questioning your terminology - I think that you are irrationalising it :smile: (actually rational/irrational don't make sense here really, but that's by the by.)

Why don't AQA like Taylor series? Surely any correct method is acceptable?


It is, but they like 'their' way of doing everything, and don't like too much deviation in your answer from the marks scheme, even if it is correct. You may even get only answer marks and not the method marks, which constitute most of the marks on these kind of questions. (Np, terminology is not my strong point :colondollar:)
Original post by zetamcfc
You may even get only answer marks and not the method marks, which constitute most of the marks on these kind of questions. (Np, terminology is not my strong point :colondollar:)


I thought most A level marking schemes gave full marks for any correct method - are they even allowed to do what you suggest? It seems rather biased against stronger students.
Reply 9
Original post by atsruser
I thought most A level marking schemes gave full marks for any correct method - are they even allowed to do what you suggest? It seems rather biased against stronger students.


What he means (I think) is that if you use a "not-intended" method where you experience a small slipup, you'd lose out on all the method marks. If you didn't and went on to get the correct answer, they'd be forced to give you the full set of marks. But if you slipped up with the intended method, you'd be less harshly penalised than slipping up with the non-intended method. That's my take (not that I agree with that practice) on it.
Original post by Zacken
What he means (I think) is that if you use a "not-intended" method where you experience a small slipup, you'd lose out on all the method marks. If you didn't and went on to get the correct answer, they'd be forced to give you the full set of marks. But if you slipped up with the intended method, you'd be less harshly penalised than slipping up with the non-intended method. That's my take (not that I agree with that practice) on it.


Yup.
Original post by Zacken
What he means (I think) is that if you use a "not-intended" method where you experience a small slipup, you'd lose out on all the method marks. If you didn't and went on to get the correct answer, they'd be forced to give you the full set of marks. But if you slipped up with the intended method, you'd be less harshly penalised than slipping up with the non-intended method. That's my take (not that I agree with that practice) on it.

Maybe - I'll have to see if I can find out for sure - are there any markers reading that can confirm this? If true, I can't see how they can justify it - you could end up with the stronger students getting much lower marks than than the weaker ones.
Reply 12
Original post by atsruser
Maybe - I'll have to see if I can find out for sure - are there any markers reading that can confirm this? If true, I can't see how they can justify it - you could end up with the stronger students getting much lower marks than than the weaker ones.


@tiny hobbit should be able to clarify matters. I share your concerns.
@atsruser @Zacken Sorry about the confusion, it does seem that any correct method which gives the correct answer will give some marks, but it does not state how many http://filestore.aqa.org.uk/subjects/AQA-MFP3-W-MS-JUN14.PDF see page 3. I would assume it was up to examiners to make the decision on the amount of marks perhaps by consulting with a senior examiner.
Original post by zetamcfc
@atsruser @Zacken Sorry about the confusion, it does seem that any correct method which gives the correct answer will give some marks, but it does not state how many http://filestore.aqa.org.uk/subjects/AQA-MFP3-W-MS-JUN14.PDF see page 3. I would assume it was up to examiners to make the decision on the amount of marks perhaps by consulting with a senior examiner.

That's a little vague, isn't it? I seem to recall having had this discussion in the past - there's probably an answer already somewhere on this site (or in the depths of Google)
Original post by zetamcfc
It is, but they like 'their' way of doing everything, and don't like too much deviation in your answer from the marks scheme, even if it is correct. You may even get only answer marks and not the method marks, which constitute most of the marks on these kind of questions. (Np, terminology is not my strong point :colondollar:)


Original post by atsruser
I thought most A level marking schemes gave full marks for any correct method - are they even allowed to do what you suggest? It seems rather biased against stronger students.


Original post by Zacken
@tiny hobbit should be able to clarify matters. I share your concerns.


Any board that I've marked for (which doesn't include AQA) allow any correct method if the question doesn't specify a particular method. The danger of doing something unexpected is that the examiner may not realise what you are doing, particularly if you make an error along the way. Make sure that your method and working are very clear (maybe even giving a brief explanation/name for your method).

A published mark scheme may not include all the details that the examiners get in their version, including mark schemes for alternative methods.
Original post by tiny hobbit
Any board that I've marked for (which doesn't include AQA) allow any correct method if the question doesn't specify a particular method...


Thanks for this - it confirms pretty much what I understood to be the case.
Original post by atsruser
That's a little vague, isn't it? I seem to recall having had this discussion in the past - there's probably an answer already somewhere on this site (or in the depths of Google)


''An element of professional judgement is required in the marking of any written paper. Remember that the mark scheme is designed toassist in marking incorrect solutions. Correct solutions leading to correct answers are awarded full marks but work must not be judged onthe answer alone, and answers that are given in the question, especially, must be validly obtained; key steps in the working must alwaysbe looked at and anything unfamiliar must be investigated thoroughly.Correct but unfamiliar or unexpected methods are often signalled by a correct result following an apparently incorrect method. Such workmust be carefully assessed. When a candidate adopts a method which does not correspond to the mark scheme, award marks accordingto the spirit of the basic scheme; if you are in any doubt whatsoever (especially if several marks or candidates are involved) you shouldcontact your Team Leader.''

OCR seem to have a decent explanation, but alas I can't find one for AQA :frown:
Reply 18
Original post by tiny hobbit
Any board that I've marked for (which doesn't include AQA)


Thank you! :smile:

Quick Reply

Latest