appleme Posted December 19, 2008 Report Share Posted December 19, 2008 Find the exact value of the x coordinate of the point of inflection on the graph of y= x2 ln(1/x2)Help, please Reply Link to post Share on other sites More sharing options...
Abu Posted December 19, 2008 Report Share Posted December 19, 2008 You can use product rule differentiation, and put the second derivative which is ƒ''(x) = 0 and then solve for x. Reply Link to post Share on other sites More sharing options...
appleme Posted December 19, 2008 Author Report Share Posted December 19, 2008 I tried that ... but I got to a stage whereln (1/x2) =5x2and i don't know where to go from there Reply Link to post Share on other sites More sharing options...
Abu Posted December 19, 2008 Report Share Posted December 19, 2008 Okay, I don't have the brain power in the night to try solving it, so here are the steps from MathwayFirst derivative: http://www.mathway.com/answer.aspx?p=ccal?...p=?p=?p=0?p=?p=Second derivative: http://www.mathway.com/answer.aspx?p=ccal?...p=?p=?p=0?p=?p=Solve: http://www.mathway.com/answer.aspx?p=ccal?...p=?p=?p=0?p=?p=That *should* be the answer. Reply Link to post Share on other sites More sharing options...
diabolicalangle Posted December 31, 2008 Report Share Posted December 31, 2008 waiiiit it says that the derivation of ln (1/x^2) is 0. isnt it 2x^3derivative of ln (u) = (1/u) * (du/dx) Reply Link to post Share on other sites More sharing options...
ezex Posted December 31, 2008 Report Share Posted December 31, 2008 (edited) *sigh* first of all make your life easier and use rule of logs to change (x^2)(ln(1/x^2)) to (x^2)(-2)(ln(x)). I know, you have no idea how that happened:Ln (1/x^2) = ln (x^-2) and by rule of logs, ln (x^a) where a is any constant = a*ln(x)hence first deriavte = -2x^2/x - 4x(ln(x)) = -2(x + 2x(ln(x)))second derivative = -2[1 + 2 + 2ln(x)]simplify a little and set it equal to zero and you get -2(3 + 2ln(x)) = 0, divide both sides by -2 subtract 3 divide by 2 and you get ln(x) = -3/2, do e to both sides and you get x = e^-3/2 or 1/(e times sqrt e)test it into your second derivative using a number line or any other way you want to see if the second derivate does in fact change signs at x = e^-3/2. If it does then its a POI if not then its...not. It does so it is a POI.by the way, I like these types of questions so anyone who reads this don't hesitate on asking anything like this cause I'll answer it as soon as I see it. Edited December 31, 2008 by ezex Reply Link to post Share on other sites More sharing options...
rojo Posted February 7, 2009 Report Share Posted February 7, 2009 I may be a new member at this forum, but I'm far from new to it. So, I'll just get straight to the point:Does anyone who has done/or is still doing Math SL know how to get a 6 or a 7? Reply Link to post Share on other sites More sharing options...
Abu Posted February 7, 2009 Report Share Posted February 7, 2009 Practice practice practice x 109453454246 Reply Link to post Share on other sites More sharing options...
Mahuta ♥ Posted February 7, 2009 Report Share Posted February 7, 2009 Yup I agree! Past papers are the key to everything.BTW Aboo what level were you? of math.oh..and welcome rojo(its not like i dont know you lol) Reply Link to post Share on other sites More sharing options...
Abu Posted February 7, 2009 Report Share Posted February 7, 2009 Yup I agree! Past papers are the key to everything.BTW Aboo what level were you? of math.oh..and welcome rojo(its not like i dont know you lol)I did HL. Reply Link to post Share on other sites More sharing options...
deissi Posted February 7, 2009 Report Share Posted February 7, 2009 There's nothing special or even tricky about getting a 6 or a 7 in SL Math. The questions are very straightforward, and I've yet to see a trick question on an IB exam. If you're good at math, a 6/7 will be automatic, and even if you're not, some studying will guarantee the mark you are looking for. Reply Link to post Share on other sites More sharing options...
rojo Posted February 9, 2009 Report Share Posted February 9, 2009 (edited) Thanks everyone for your help I think I'll stick to doing as many past papers as I humanly can. Edited February 9, 2009 by rojo Reply Link to post Share on other sites More sharing options...
__inthemaking Posted February 9, 2009 Report Share Posted February 9, 2009 It's not difficult to get a 7 in math SL. Just do all the past papers that you can get your hands on and you're good to go. I wrote my math SL exam in May 2007 and I had done all the past papers from 1998-2006 (May and November) lol. Reply Link to post Share on other sites More sharing options...
rojo Posted February 9, 2009 Report Share Posted February 9, 2009 Looks like you nailed it Thanks for reiterating the advice __inthemaking* Reply Link to post Share on other sites More sharing options...
steam.rice.sally Posted February 12, 2009 Report Share Posted February 12, 2009 In my IB program, math is only offered as a Standard Level course. I took Math Studies in my Junior year of high school and tested out, so I can't take the same course in my Senior year. This year, I am taking Calculus, and I am having serious trouble understanding, and especially remembering, the steps to solve problems. Is there any way to easier understand Mathematics SL and is there applications for calculus? Reply Link to post Share on other sites More sharing options...
Abu Posted February 12, 2009 Report Share Posted February 12, 2009 You just have to keep on practising in order to understand the problems effectively. What do you mean by applications? Reply Link to post Share on other sites More sharing options...
Ashika Posted February 12, 2009 Report Share Posted February 12, 2009 By applications, if you mean word problems, yes there is. For differential calculus there's optimization and maxima/minima problems.For integrals there's physics type problems and things like finding area under the curve etc.As for learning calculus, know your rules!And like Aboo said, practice!Do every problem in your book if that's what it takes.That's generally what I try to do before calculus exams (like the one I have tomorrow ) Reply Link to post Share on other sites More sharing options...
greese Posted February 12, 2009 Report Share Posted February 12, 2009 1. Derive y = sin (root x)I think it is (1/2) x ^(-1/2) cos (root x)2. Integrate cos^(2) xI have no idea3. Find the volume when the region bounded by y = sin x, y = cos x, the x axis and x = pi/2 is rotated 360 degrees around the x - axis.I know I need to integrate y^2, however do i complete these integrals individually between 0 to pi/2 and pi/2 to pi/4 or something else. And of course in order to do this i need to be able to do #2. Reply Link to post Share on other sites More sharing options...
Mahuta ♥ Posted February 12, 2009 Report Share Posted February 12, 2009 When you say derive do you mean differentiate?If so, its simply [cos(x^-1/2)]/2 Reply Link to post Share on other sites More sharing options...
greese Posted February 12, 2009 Report Share Posted February 12, 2009 When you say derive do you mean differentiate?If so, its simply [cos(x^-1/2)]/2yes i did mean differentiate. sorry. But can you explain your solution because i am missing it.thanks for your help Reply Link to post Share on other sites More sharing options...
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