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  1. KFunk

    Can someone please explain this? (Log and Exp)

    I reckon the 'e' method makes life easier. Luthian, in your first post it's just subbing in e<sup>ln2</sup> for 2 because 2<sup>x</sup> = e<sup>x.ln2</sup> so your working is: y = 2<sup>x</sup> = (e<sup>ln2</sup>)<sup>x</sup> = e<sup>x.ln2</sup> dy/dx = ln2.e<sup>x.ln2</sup> =...
  2. KFunk

    Scales on the Axes

    I might not call you pedantic but I would certainly dare you to draw x<sup>2</sup>/1000 + y<sup>2</sup>/900 = 1 to 'scale' on A4 paper.
  3. KFunk

    help !!

    I would if I had the time at the moment (HSC and whatnot). If you're cool with posting your questions on the board then there are more than enough people to tackle them. I geuss right now the board is good because we can be selective in what we do.
  4. KFunk

    Quick graphs question

    I remember debating this some time ago and the conclusion we ended up with was that you can safely treat undefined x values of f(x) as zeros of 1/f(x). Examples exist where this is not the case but I don't think we have to worry about it for the level we're working at and given the kind of...
  5. KFunk

    help !!

    Haha, yeah, except for the fact that I got nothin' when it comes to circle geometry and conics. Those two topics, along with my stupid mistakes, kill me.
  6. KFunk

    help !!

    The resistive force gives you the equation of motion which is: acceleration = v(dv/dx) = -v&radic;(1 - v<sup>2</sup>) dv/dx = - &radic;(1 - v<sup>2</sup>) dx/dv = -1/&radic;(1 - v<sup>2</sup>) then integrate w.r.t. v to get x = cos<sup>-1</sup>v + c ... when x=0, v=R so c =...
  7. KFunk

    [Question] for the exam!

    From the Wolfram site: "A function is monotonic if its first derivative (which need not be continuous) does not change sign." As has been said monotonic increasing is where the gradient is always positive, and simarly I assume monotic decreasing is where the gradient is always negative.
  8. KFunk

    Binomial Theorem Proof

    Here's an example of where this can become useful. You could extend the logic of it to show that the coefficient of 1<sup>n- k</sup>x<sup>k</sup> = n!/k!(n-k)! = <sup>n</sup>C<sub>k</sub>. Alternatively consider (1 + x)<sup>n</sup> = (1 + x)(1 + x)... (1 + x) --> n times. The number of ways...
  9. KFunk

    another complex number question

    You're allowed to just assume it. However, you have to first recognise that the polynomial has real coefficients. Basically you say "P(x) has real coefficients hence if it has a complex root then the conjugate must also be a root. 1 - 2i is a root &there4; 1 + 2i is also a root." If you're...
  10. KFunk

    probability qs

    Because you have doubles matches I think you have to split them into groups of 4 first so the way I'm looking at it it's like: <sup>8</sup>C<sub>4</sub>/2 = the number of ways to make two unique groups of 4 from 8. For group one there are <sup>4</sup>C<sub>2</sub>/2 ways to make two unique...
  11. KFunk

    polynomials question

    Here's the way it makes sense to me. First off show that p divides b and q divides a so sub x = p/q into the equation: ap<sup>3</sup>/q<sup>3</sup> - 3p/q + b = 0 ap<sup>3</sup> - 3pq<sup>2</sup> + bq<sup>3</sup> = 0 bq<sup>3</sup> = p(3q<sup>2</sup> - ap<sup>2</sup>) = pR<sub>1</sub>...
  12. KFunk

    conics (is the devil)

    I felt that the up and coming 2006 young'ns had to be warned. I attached an image this time so that they can recognise satan when he starts to rise out of the page. (P.S. - you have the world's best 4U folder)
  13. KFunk

    trig functions

    LHS = 2tanx/(1-tan<sup>2</sup>x).cotx = 2/(1 - tan<sup>2</sup>x) = 2cos<sup>2</sup>x/(cos<sup>2</sup>x - sin<sup>2</sup>x) (multiplying through by cos<sup>2</sup>x) = (cos<sup>2</sup>x + cox<sup>2</sup>x)/(cos2x) = (cos<sup>2</sup>x - sin<sup>2</sup>x + 1)/cos2x .... (since...
  14. KFunk

    conics (is the devil)

    Ussually it's a given that conics = le bash algebraique but I don't see why you shouldn't be able to use conic definitions in your proof. I'd probably go with the bash (which isn't too bad, relatively speaking) in order to make sure I got the marks. Btw:
  15. KFunk

    Differentiate This!

    Another way you could do it is using the property (a)<sup>n</sup> = e<sup>n.ln(a)</sup>, if you do this then: y = 1.1<sup>n</sup> = e<sup>n.ln(1.1)</sup> dy/dn = ln(1.1)e<sup>n.ln(1.1)</sup> = ln(1.1)(1.1<sup>n</sup>) or = ln(1.1)y
  16. KFunk

    financial mathematics

    Well, if they gave an "or otherwise" option then: http://www.braungardt.com/Theology/Godel-Proof%20of%20God.htm
  17. KFunk

    Newcastle Med

    I think I got something like the 24th. It was very lucky because the day after that I'm heading up to brisbane to catch Oasis and then going back down to Byron for schoolies. Another date could have been very messy.
  18. KFunk

    financial mathematics

    ohoh... there are formulas?
  19. KFunk

    Got a tricky question!

    Nice method, it's very simple. I geuss you can safely assume that u<sub>n</sub> --> &infin; as n--> &infin; but first would you show that there is a term u<sub>k</sub> where u<sub>k</sub> > 1 or just not bother?
  20. KFunk

    Mr. and Mrs. X

    But the way the question is phrased suggests that that situation is not a possibility. Alternatively I geuss you could say that the people picking the comitee members are unaware of Mr X's issues so they might inadvertently create that conflicting situation but then doesn't that just disregard...
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