deissi Posted February 24, 2009 Report Share Posted February 24, 2009 With limitations, the negative values, for log(a)c=xlog(-2)-8=3 mathematically this is correct because (-2)^3 is 8. But when you are dealing with what you are in your project it doesnt.(-2)3 = (-2)*(-2)*(-2) = -8. =)few questions...I did that, but my teacher says we have to explain why graphing it can justify.. like, I see a pattern, but I have no idea how to explain how what I'm looking at helps justify the pattern.Well yeah, you should be able to explain why it only works after a certain number. However, I can't tell you what the reason is. It shouldn't be too difficult when you really look at it. Still, it's better to have a graph with the correct domain and no explanation, than no graph at all. This is because criterion X (I forget which one..) says that for the top mark, you need to have the correct limitation, but it does not state that you need to prove how you found it. That's more of a criterion B (communication) issue. Reply Link to post Share on other sites More sharing options...
ricochet Posted March 9, 2009 Report Share Posted March 9, 2009 i'm working on doing my final write-up for this portfolio '(I'm supposed to turn it in tomorrow) and i just realized that I never did justify my answers using technology. I know i could convert all the logs to base 10 or make an excel tables of all the p/q values (i'm on the right track, right?), but i'm not sure how doing either of those things would "justify" my answers. Could someone please help me understand this? Also, are there any other methods of using technology that would be useful in this situation? Thanks so much in advance for any help you can give me! Reply Link to post Share on other sites More sharing options...
LinuxBeta Posted March 9, 2009 Report Share Posted March 9, 2009 I'm not sure about what the portfolio asks, does it ask explicitly for proof using technology? If it is just to get marks on the technology criterion, then an excel table is fine. Technology is supposed to help you, and also allow you to see that while it is useful, there are limitations. Reply Link to post Share on other sites More sharing options...
ricochet Posted March 9, 2009 Report Share Posted March 9, 2009 It says, "Find an expression for the nth term of each sequence. write your expressions in the form p/q where p, q E Z. Justify your answers using technology." so it sounds to me like you don't have to find your answers using technology, just verify that they are correct in some way. So you think an excel table of the p/q values i found would somehow fulfill that requirement? Reply Link to post Share on other sites More sharing options...
faerie Posted March 9, 2009 Report Share Posted March 9, 2009 i'm working on it right now too (due tomorrow... *sigh*). i'm actually typing it to try to get the technology points. people keep saying something about graphing it, but i don't understand that... Reply Link to post Share on other sites More sharing options...
ricochet Posted March 9, 2009 Report Share Posted March 9, 2009 I know, I don't really see how graphing would help justify our answers. I ended up making an Excel table for each sequence and spouting some BS about how my "logical method" of finding the expressions was "confirmed mathematically" by the formulas in Excel. Phooey. well, it kind of sounds legit, even if it turns out not to be. Well, good luck with your portfolio, Faerie! Reply Link to post Share on other sites More sharing options...
joshsson Posted March 12, 2009 Report Share Posted March 12, 2009 okay, i am sooooooooo confused on this portfolio right now.in number 2, where they say "Find an expression for the nth term of each sequence. Write your expressions in the form p/q, where p,q Є Z"what does that symbol before z mean?do they want an expression, as in, p^(0+1)/q, like a formula to find any term?i know the bases in the sequences in #1 are going up by exponents of 1, because in the first term, it's 2, and in the second, 4, which is 2 squared.but how do i put that in a fractional form? gahhhhhh so bewildered. Reply Link to post Share on other sites More sharing options...
deissi Posted March 13, 2009 Report Share Posted March 13, 2009 Z means integers. Click on the link if you don't know what integers are, it's very simple. It won't be p^x, but rather something like p*x/q, p/x/q, p+x/q, p-x/q. The change might also take place in q instead of p! I won't tell you which one, you'll have to find out for yourself.When you solve the examples, finding the fractional form will be clear enough. Reply Link to post Share on other sites More sharing options...
australiANgel Posted March 14, 2009 Report Share Posted March 14, 2009 hello everyone,it says that you need to test the validity of your general statement using other values of a,b and xdoes this mean that you make up other examples, or do you use the ones that they have already given you?and you guys said that log(ab)x =???.. how did you come up with that?thank you! =) Reply Link to post Share on other sites More sharing options...
deissi Posted March 14, 2009 Report Share Posted March 14, 2009 Use your own examples to show the validity.We cannot tell you how to find the general statement, this is the only remotely difficult task in the IA and it constitutes malpractice to use someone else's work for this part.In fact, I'll remove the general statement from your post and previous posts now. Reply Link to post Share on other sites More sharing options...
gangofgiraffes Posted March 18, 2009 Report Share Posted March 18, 2009 how do you justify your answer using technology? do you graph it? if so can u just graph it on a calculator or do u have to use a program like microsoft excel? Reply Link to post Share on other sites More sharing options...
Mahuta ♥ Posted March 19, 2009 Report Share Posted March 19, 2009 Justifying using technology could be using the GDC to work out logs and stuff after changing the base. That's what I did atleast. Reply Link to post Share on other sites More sharing options...
Lancevol Posted March 20, 2009 Report Share Posted March 20, 2009 First off, thanks a lot guys, this thread has really helped me get on the right track with this portfolio. Now, I'm currently on the part where I find the general statement. I think I know what it is, and I know how to prove it using logarithm laws, but I'm a little confused by the prompts.It tells me to find the general statement. Fine, I can do that, but then at the very END of the portfolio it asks me to explain how I arrived at it. When I first say the general statement should I just cite the fairly obvious pattern and leave the logarithm laws for later? If I just proved it with logarithm laws now would that count as answering that final prompt? Sorry if the answer is obvious, I just don't want to lose marks for a stupid reason =) Reply Link to post Share on other sites More sharing options...
IB:Spartan Posted March 20, 2009 Report Share Posted March 20, 2009 (edited) First off, thanks a lot guys, this thread has really helped me get on the right track with this portfolio. Now, I'm currently on the part where I find the general statement. I think I know what it is, and I know how to prove it using logarithm laws, but I'm a little confused by the prompts.It tells me to find the general statement. Fine, I can do that, but then at the very END of the portfolio it asks me to explain how I arrived at it. When I first say the general statement should I just cite the fairly obvious pattern and leave the logarithm laws for later? If I just proved it with logarithm laws now would that count as answering that final prompt? Sorry if the answer is obvious, I just don't want to lose marks for a stupid reason =)I have the same problem. I try to prove it i state the statment, but then i would lose marks.I also have trouble with the "discuss the scope and/or limitations of a, b, and x."I don't quite understand what they mean by the scope. I get how in logabx, x cannot equal zero, and the demoninator cannot equal zero, but what about the scope? Edited March 20, 2009 by IB:Spartan Reply Link to post Share on other sites More sharing options...
Lancevol Posted March 20, 2009 Report Share Posted March 20, 2009 Hmmm, for scope I would say think of some numbers that DO work with it. Not just integers. I don't know how much more info I can give, and I'm not too good with hints =[ Reply Link to post Share on other sites More sharing options...
Mahuta ♥ Posted March 20, 2009 Report Share Posted March 20, 2009 Values dont have to be just integers, include all kinds of numbers: rational, irrational, fractions..etc. I can say that the most important part is the one you're doing right now, the verification and the scope and limitations. Reply Link to post Share on other sites More sharing options...
deissi Posted March 20, 2009 Report Share Posted March 20, 2009 Scope: does it work from negative infinity to infinity? If not, what is the scope?About the general statement: You can botha) first find the general statement deductively (i.e. by examples) and later solve it algebraically when it asks you how you arrived to it.b) find the general statement algebraically and thus solve the problems. There is no need to restate the solution, but it is a good idea to state something along the lines "Using algebra, we will show the general statement is found as follows:" to make sure that your teacher will know that this is you proving how you found the general statement. I did this and I got full marks for the criterion. Reply Link to post Share on other sites More sharing options...
Mahuta ♥ Posted March 22, 2009 Report Share Posted March 22, 2009 Wanderer:Excuse me?1)You procarastinated a project that should have taken 10 days at least of your time.2)We do NOT send or share portfolios because that is against IB Regulations.3)We're not going to help you unless you make an attempt.4)Do not urge people to help you in that way.5)Don't text speak.(I know Joel , it came in context). Reply Link to post Share on other sites More sharing options...
wanderer Posted March 23, 2009 Report Share Posted March 23, 2009 Wanderer:Excuse me?1)You procarastinated a project that should have taken 10 days at least of your time.2)We do NOT send or share portfolios because that is against IB Regulations.3)We're not going to help you unless you make an attempt.4)Do not urge people to help you in that way.5)Don't text speak.(I know Joel , it came in context).Hey don't get all mad at me...i finished working out the portfolio i just do not know what format to write it down in..my teacher says it should be a continuous piece of work.. i just don't know how to do that..i have a rough draft ready but as i have never done a portfolio before in my life i have no idea how is it supposed to be like..i was just wondering if you guys could help me with that.. thus i wanted to view someone else's portfolio to get a hang of how i am supposed to write it down..besides i want to know which graph software to use for my portfolio... Reply Link to post Share on other sites More sharing options...
deissi Posted March 24, 2009 Report Share Posted March 24, 2009 It doesn't take much reading to find what graph software people have used. Try Graphical Analysis 3.4.We're all in the same situation where we don't know what a portfolio looks like, but we all have to figure it out for ourselves. It's tough, but that's IB. Reply Link to post Share on other sites More sharing options...
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