micogo Posted May 22, 2013 Report Share Posted May 22, 2013 Hey guys, how did you find the Series and Differential Equations paper 3?!It was amazing in my opinion. The best out of all three math papers. There wasn't even one question where a convergence test was needed apart from the interval and radius of convergence one. The only one I definitely lost marks on was the one with the summation from 1 to infinity of (n^2 * x^n)/(2^n), when it said find the sum of the series given that x= -0.1. Did anyone manage that? Reply Link to post Share on other sites More sharing options...
IB-Adam Posted May 22, 2013 Report Share Posted May 22, 2013 The only one I definitely lost marks on was the one with the summation from 1 to infinity of (n^2 * x^n)/(2^n), when it said find the sum of the series given that x= -0.1. Did anyone manage that?You had to realise that it was an alternating series and to some error analysis. I found that the sum of the first 4 terms would give me the sum correct to 3 sig.Didn't get the telescoping series... The last question with the upper, and lower bounds were actually really easy although it got stressed in the end.Grade boundaries are going to be high this year. 50/60 for a 7. Reply Link to post Share on other sites More sharing options...
Zuler Posted May 22, 2013 Report Share Posted May 22, 2013 The only one I definitely lost marks on was the one with the summation from 1 to infinity of (n^2 * x^n)/(2^n), when it said find the sum of the series given that x= -0.1. Did anyone manage that?You had to realise that it was an alternating series and to some error analysis. I found that the sum of the first 4 terms would give me the sum correct to 3 sig.Didn't get the telescoping series... The last question with the upper, and lower bounds were actually really easy although it got stressed in the end.Grade boundaries are going to be high this year. 50/60 for a 7.I agree, but maybe a little lower since it wasn't AS easy as 2012, so maybe 48+ Reply Link to post Share on other sites More sharing options...
ApotheoCarp Posted May 23, 2013 Report Share Posted May 23, 2013 I loved this paper. It was definitely one of the simpler ones I've seen. I might have made a careless mistake on the summation to infinity, since I wasn't sure about significant figures so I kept crossing things out and rewriting the answer, and eventually I may have forgotten to write down the minus sign. Just to be sure, was it supposed to be -0.0410? Reply Link to post Share on other sites More sharing options...
halocheese Posted May 23, 2013 Report Share Posted May 23, 2013 Yes, it was -0.0410, but you had to show how you got there using the Alt. Estimation Theorem i.e. I S - S(n) I < a(n+1). You either had to use n=4 or 5 to give you the answer, I don't remember which I used though! Reply Link to post Share on other sites More sharing options...
ApotheoCarp Posted May 23, 2013 Report Share Posted May 23, 2013 I'm pretty sure I used it... Well, I'll hopefully at least get some points for the rest of that question if I didn't.Thankfully the rest of the paper was relatively easy. There weren't any shocking questions like 2011. Reply Link to post Share on other sites More sharing options...
IB-Adam Posted May 23, 2013 Report Share Posted May 23, 2013 I wasted a lot of time thinking that the base length of the rectangles were a instead of 1. Wrote a lot of "see other booklet" so I am probably going to piss off the examiner Reply Link to post Share on other sites More sharing options...
Zuler Posted May 23, 2013 Report Share Posted May 23, 2013 Overall, as you guys said, it was really easy. The first question my limit was 1/2. The third question, my interval was from -2 < x < 2, cause mine diverged at both the endpoints? And the fourth question, my a was 3 and b was 5, and my limit was 3/4. The last question, a was 11 in the first part and 6 in the second? Reply Link to post Share on other sites More sharing options...
bomaha Posted May 23, 2013 Report Share Posted May 23, 2013 Yes, Zuler I got everything you said. I got the differential equation in Q2 to be "y= (sinx)(cosx) + 2cosx"? Reply Link to post Share on other sites More sharing options...
Usman Khan Posted May 23, 2013 Report Share Posted May 23, 2013 Did anyone do the stats option? Reply Link to post Share on other sites More sharing options...
micogo Posted May 23, 2013 Author Report Share Posted May 23, 2013 I got exactly those Zuler, as far as I remember. ^^ Reply Link to post Share on other sites More sharing options...
micogo Posted May 23, 2013 Author Report Share Posted May 23, 2013 The only one I definitely lost marks on was the one with the summation from 1 to infinity of (n^2 * x^n)/(2^n), when it said find the sum of the series given that x= -0.1. Did anyone manage that?You had to realise that it was an alternating series and to some error analysis. I found that the sum of the first 4 terms would give me the sum correct to 3 sig.Didn't get the telescoping series... The last question with the upper, and lower bounds were actually really easy although it got stressed in the end.Grade boundaries are going to be high this year. 50/60 for a 7.I realized it was an alternating series, but I decided to complicate things by integrating it from 1 to infinity to find the sum, which was taking ages so I skipped it. Derp. Easy marks lost. Reply Link to post Share on other sites More sharing options...
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