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  1. J

    Australian Maths Competition

    Re: Australian Maths Competition 2013 ye it is probably 126. Nevertheless this is what I did, probably I missed something haha http://imgur.com/a/fsfVN
  2. J

    Australian Maths Competition

    Re: Australian Maths Competition 2013 If its asking for the maximum number of chords without intersection, not number of ways, then I think its 125, idk though, 75% sure its wrong.
  3. J

    Prelim 2016 Maths Help Thread

    the vertex is actually (1,3). So the focal length is 3 units so you move 3 units right of the vertex (since negative y^2=4ax) to get the directrix which is x=4
  4. J

    Prelim 2016 Maths Help Thread

    You made a mistake when solving k^2+k-2>0, it should be k>1 or k<-2
  5. J

    2017ers Preliminary Chit Chat Thread

    Ye heard 17/30 was the cut off for HD too. But don't worry I'm pretty average at chem and found it pretty easy to okay-ish difficulty, I bet you'll do good haha. So ye good luck tomorrow!
  6. J

    Pokemon GO thread

    finally got 3g to play pokemon
  7. J

    Prelim Physics Thread

    Ah okay thankyou!
  8. J

    Prelim Physics Thread

    please help, an explanation if possible. Thanks
  9. J

    2017ers Preliminary Chit Chat Thread

    Anyone did the ANCQ yesterday?
  10. J

    Principle of relativity question

    http://community.boredofstudies.org/263/space/253170/how-did-aether-model-violate-principle-relativity.html found a thread, may be helpful idk
  11. J

    HSC 2016 Maths Marathon (archive)

    Re: HSC 2016 2U Marathon haha ye remember it from this youtube vid, funny indeed lol
  12. J

    HSC 2016 MX2 Integration Marathon (archive)

    Re: MX2 2016 Integration Marathon I= \int \tan ^4x\cos 2x $ d$x \\ $ applying IBP; $ u=\tan ^4x \Rightarrow $ d$u=4\tan ^3x\sec ^2x, \\ $ d$v=\cos 2x \Rightarrow v=\sin x\cos x\\ \\I=\tan ^4x\sin x\cos x-4\int \tan ^3x\sec ^2x \sin x \cos x$ d$x \\ = \sin ^2x\tan ^3x-4\int \tan ^4x$ d$x \\...
  13. J

    HSC 2016 MX2 Integration Marathon (archive)

    Re: MX2 2016 Integration Marathon Woah that's actually pretty helpful, thanks :)
  14. J

    HSC 2016 MX2 Integration Marathon (archive)

    Re: MX2 2016 Integration Marathon I =\int \frac{\sqrt{1+x^2}}{x} $d$x \\ $ let $ u=\sqrt{1+x^2} \Rightarrow $ d$x=\frac{\sqrt{1+x^2}}{x}$ d$u \\ I = \int \frac{u^2}{u^2-1}$ d$u$ $ = \int 1+\frac{1}{u^2-1}$ d$u \\ $ let $\frac{A}{u+1}+\frac{B}{u-1}=\frac{1}{u^2-1} \\ $ by expanding and...
  15. J

    Need help please

    oh yeah soz
  16. J

    Need help please

    $recall that the formula to find the volume of a curve rotated about the x-axis from $ a $ to $ b$ is : $ \pi\int_{a}^{b} y^2 $ d$x. $ Here $ y = \cos \pi x $ and the limits are from 0 to 1, so plugging in the values and integrating, you get $: \\ V=\pi\int_{0}^{1} \cos^{2}( \pi x) $ d$x \\ =...
  17. J

    Question need help immediately

    yeah InteGrands answer is right
  18. J

    HSC 2016 MX2 Integration Marathon (archive)

    Re: MX2 2016 Integration Marathon since no one did this, I gave it a try; I=\int\frac{\sin x-\cos x}{(\sin x+\cos x)\sqrt{\sin x\cos x+\sin^2 x\cos^2 x}}$ d$x \\ $ let $u=\sin x\cos x \Rightarrow $ d$u=(\cos ^2x-\sin ^2x)$ d$x\\ \therefore $ d$x=\frac{ du}{(\cos x+\sin x)(\cos x-\sin x)}...
  19. J

    Girraween HAST test for yr11 2016

    I think it's a quote haha
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