Outis Posted May 3, 2012 Report Share Posted May 3, 2012 The dreaded math sl exams are finally close to over.I have created this topic so that fellow ibers can discuss the questions on either one of these tests.REMEMBER: DISCUSSION IS NOT ALLOWED UNTIL 24HOURS HAVE PASSED 2 Link to post Share on other sites More sharing options...
The Economist Posted May 3, 2012 Report Share Posted May 3, 2012 So why make this thread now? 1 Link to post Share on other sites More sharing options...
Noxen Posted May 3, 2012 Report Share Posted May 3, 2012 Easy Peasy Lemon Squeezy! Link to post Share on other sites More sharing options...
Vincent Casey F Posted May 4, 2012 Report Share Posted May 4, 2012 I'm guessing it has been 24 hours?TZ2 was pretty easy! I really didn't struggle with anything muchOnly the Binomial question was new to me! I got n=21And I made a stupid mistake with integrating the function for the area under the curve one! :\ I felt like crap when I found out what I did (integrated 13x instead of 13.. so my answer was 6.5(x)2 instead of 13x)And I wanted to ask this. Last part of the last question (for what values of k is y=k ?.. or something like that), what did you guys do there? I said 1/9>k>1 cause local minimum was f(1/9) and local maximun was f(1) and there was this gap there that if k=y for 1/9>k>1 wouldn't touch the graph. Is that right?Overall it was easier than my mock and most IB past papers! I even found it easier than May 2011.. Aiming for 70 to 80 out of 90Just came back from my paper 2 but can't discuss that now muhahaha! Link to post Share on other sites More sharing options...
Ageha Posted May 4, 2012 Report Share Posted May 4, 2012 Hmm.....Paper 1 was not too difficult, I guess.The only question I was surprised with at first glance was the binomial one, but I got n= 14. Vincent Casey F, are you sure its 21?One more question I was wondering about was the question about the equation of the normal to the graph.The first part of the question asked for the tangent of the curve at the minimum point, which I think we all figured out quite easily, but the second part of the question asked about the equation of the normal to the graph at that minimum point, the point I think was (2,3) or something similar.What did you guys answer that question with? Link to post Share on other sites More sharing options...
ILM Posted May 4, 2012 Report Share Posted May 4, 2012 I think n is 7, 2n= 14 Link to post Share on other sites More sharing options...
Ageha Posted May 4, 2012 Report Share Posted May 4, 2012 Some of friends also mentioned a similar answer, but I do not remeber getting 2n...:S Link to post Share on other sites More sharing options...
uusinjsh Posted May 4, 2012 Report Share Posted May 4, 2012 (edited) I also got n=7 since you had to consider two terms, which had x in the 1st power, eventually I got 6xn+6xn = 84x 12xn=84x x=7. Anyone else supporting this?As for normal, gradient of tangent was 0, since it was at minimum point, thus obviously horizontal (y=-3), so if normal to the curve is perpendicular to that, it is vertical thus x= 2.The one with y=k stuff, I got interval (1/9;1) Edited May 4, 2012 by uusinjsh Link to post Share on other sites More sharing options...
Ageha Posted May 4, 2012 Report Share Posted May 4, 2012 I got the 12xn = 84x too, but I substituted by (6/x) or something similar for n and I got the answer as 14...Well....the gradient one was quite easy, but isn't the equation of the normal x=2?I got a similar asnwer for the y=k. Link to post Share on other sites More sharing options...
Guest CasaNova Posted May 4, 2012 Report Share Posted May 4, 2012 haha... my classmates also got results like the others; n=7;14:21:13.. personaly i believe it is 7 since the best student in out class got 7 i got 14 just like ageha.. but probably for 7 points you did not have to do one line of calculations but to use the binominal formula and so.. Link to post Share on other sites More sharing options...
uusinjsh Posted May 4, 2012 Report Share Posted May 4, 2012 Yes, my mistake, x=2.If you get 12xn = 84x, how can n not be 7 o_ODid you get 10 square units for the area? Link to post Share on other sites More sharing options...
Ageha Posted May 4, 2012 Report Share Posted May 4, 2012 Hmm...I used the bionamial theroem to find the answer, and I has to use twice, for different values of r...Have you guys tried solving it regularly? By using your answers to check? Link to post Share on other sites More sharing options...
Ageha Posted May 4, 2012 Report Share Posted May 4, 2012 Oh....sorry....I'll check again....And yea, I got the area as 10 too Link to post Share on other sites More sharing options...
uusinjsh Posted May 4, 2012 Report Share Posted May 4, 2012 I remember clearly when doing past exams that once you had to identify term with particular power at x, and it told in markscheme that the term added up from two separate ones..Since you get 6xn when multiplying 1 from 1st brackets to 6xn from 2nd.. AND 9 from 2nd brackets with a term that has x in the 1st power from first brackets.It is the second term, which thus stands (n C 1) 1^(n-1) (2x/3)^(1), which is n * 1 * 2x/3 ==> 9 * 2xn/3 = 6xnHence two times 6xn. 12xn = 84x. x=7 Link to post Share on other sites More sharing options...
Ageha Posted May 4, 2012 Report Share Posted May 4, 2012 Hmmm....just to be sure....the equation was (1+(3/2)x)^n (3+nx)^2....no?I am trying to check the answers by substituting n for the different values, 7 and 14... Link to post Share on other sites More sharing options...
Guest Posted May 4, 2012 Report Share Posted May 4, 2012 I definitely thought that this was the easiest Paper 1 I've seen, which I was pretty chuffed about. I also got n = 7 (glad to see other people got the same!) For the equation of the normal, I got x = 2 as well. Area = 10 too For y = k, I only managed to find an asymptote at y = 1/5. I wrote something about it being possible for k to be anywhere between the minimum and maximum points on the graph, so maybe I'll get some salvage points for that The question with the two repeated roots and you had to find the value of k - did that seem familiar to anyone else? I swear I did that question on a past paper recently (I wasn't complaining though, nice to get something you're familiar with!) Overall I was pretty happy with the paper Link to post Share on other sites More sharing options...
uusinjsh Posted May 4, 2012 Report Share Posted May 4, 2012 I believe it was (1+ 2x/3) ^ n * (3+nx)^2 Link to post Share on other sites More sharing options...
Beastern Posted May 4, 2012 Report Share Posted May 4, 2012 hey. I also got n=7, and there is no one who would know the right answer for sure, all my classmates also got values like 7, 14 and 13... Link to post Share on other sites More sharing options...
uusinjsh Posted May 4, 2012 Report Share Posted May 4, 2012 As for two equal roots, i think i got k= 3 & -1 Link to post Share on other sites More sharing options...
Beastern Posted May 4, 2012 Report Share Posted May 4, 2012 I got the area equal to 10, too. Regarding the two equal roots I got k=3, and did not really manage to get -1. Hm, what else was more difficult? Link to post Share on other sites More sharing options...
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