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  1. Sy123

    ruse question 9 2003 trial

    \frac{dL}{dx}=\frac{x}{\sqrt{x^2+25}}+\frac{x-3}{\sqrt{25-6x+x^2}} \\ \\ -\frac{x}{\sqrt{x^2+25}}=\frac{x-3}{25-6x+x^2} \\ \\ \frac{x^2}{x^2+25}=\frac{x^2-6x+9}{25-6x+x^2} From there cross multiply, you will get cubic terms and a quartic terms, however they will cancel out. You are left with...
  2. Sy123

    Trig Question - HSC Exam Style 3U

    Carrotsticks cancelled out cos x, so in the given domain, he can because cos x =/= in that domain. (I think) EDIT: I graphed both sides of the equation on Geogebra, and they seem to be the exact same for all values of x, I was guessing that they might of given you that domain, because it was...
  3. Sy123

    Best 5 games you ever played:

    Definitely, R&C3 is easily the best Ratchet and Clank game, followed closely by Ratchet and Clank 1. Anyway my list cannot rank, because I cant rank them, but they are my top 5 if I had to choose 5, they arent in any order of superiority. -Ratchet and Clank 3 -Minecraft -Pokemon Pearl...
  4. Sy123

    functions and relations HELP!!!

    y=ax^3+bx \\ y'=3ax^2+b \\ x=1 \Rightarrow y'=2 \ \ \ \ ($Since tangent at$ \ x=1 \ $parallel to line gradient of 2$) \\ \therefore 2=3a+b \\ \\ x=1 \Rightarrow y=7 \\ \\ \therefore 7=a+b \\ \\ 2=3a+b \ \ \ [1] \\ 7=a+b \ \ \ [2] \ \ \ \ [1]-[2] \\ \\ \\ a=\frac{-5}{2} \\ \therefore...
  5. Sy123

    What are the hardest 4 unit topics

    So is it wise to look up 4u questions on Harder 3u Circle Geometry, as some practise in 3u circle geometry? Because I wish to do those questions faster, because they usually slow me down while Im doing trial papers.
  6. Sy123

    delelted sorry

    delelted sorry
  7. Sy123

    HSC 2012 MX1 Marathon #2 (archive)

    Re: HSC 2012 Marathon :) $Prove that for all integers$ \ \ n>0 \\ \\ x^n \neq \ln{x} Its a question entirely possible within 3u boundaries (depending on how you do it you will have to use 3u knowledge) I made the question up after I proved that result. So enjoy :3
  8. Sy123

    HSC 2012 MX1 Marathon #2 (archive)

    Re: HSC 2012 Marathon :) \ddot{x} =-n^2 x \\ \frac{1}{2}v^2=\frac{-n^2 x^2}{2}+C \\ \\ x=a \rightarrow v=0 (\text{Where a is extremety}) \\ \\ \therefore C=\frac{n^2 a^2}{2} \\ v^2=-n^2 x^2+n^2 a^2 (2\sqrt{2})^2=-9n^2+n^2 a^2 \\ \\ 8=-9n^2+n^2 a^2 \\ \\ \Abs{\ddot{x}}=1 \ \ \ when \ \ \...
  9. Sy123

    My perfect pokemon white team

    Ill go through each team member individually Haxorus: The EVs are in the right place somewhat, however replacing Swords Dance withDragon Claw as a secondary Dragon attack to not get locked into, and putting a Choice Scarf on Haxorus will benefit it and willl give you a nice late game sweeper...
  10. Sy123

    Rep: for or against poll

    Generally within most forums, if you lurk around for a bit, its easy to spot who are the popular ones, helpful etc. For example in the Math section which I lurk alot, there are many users, if I need help with something, I can count on their genius to help me out, and I have gathered such...
  11. Sy123

    Hard 3u/4u past papers

    If anyone could, a nice hard 3u past paper would be very much appreciated. Thanks.
  12. Sy123

    HSC 2012 MX1 Marathon #2 (archive)

    Re: HSC 2012 Marathon :) Show that \sin{\cos^{-1}{x}}=\sqrt{1-x^2} \ \ \text{For all x} -1\leq x\leq 1 Difficulty: Easy I will have a better one tommorow.
  13. Sy123

    HSC 2012 MX1 Marathon #2 (archive)

    Re: HSC 2012 Marathon :) \begin{align*}\ddot{x}&=-16x \\ \left(\frac{1}{2}v^2\right)\frac{d}{dx}&=-16x \\ \frac{v^2}{2}&=-8x^2+C \\ \\ x=3 \Rightarrow v=16 \\ \frac{16^2}{2}&=-8(3)^2+C \\ C=200 \\ \frac{v^2}{2}&=200-8x^2 \\ v^2&=400-16x^2 \\ v&=+\sqrt{16(25-x^2)} \\ v&=+4\sqrt{25-x^2} \\ \\...
  14. Sy123

    Ratio of All Angles in Exact Form

    Err, yes, but Im ALSO asking whether alpha needs to be an integer, or can it just be rational, or can it just be any real number of alpha. Also, a b and c should be integers
  15. Sy123

    Ratio of All Angles in Exact Form

    So I had formed a hypothesis that: \sin {\alpha} =a+b\sqrt{c} Where alpha is any integer degree. Could I write the sine of that angle, be it any angle, in exact form And a, b and c are all integers. Now the above RHS is probably wrong (maybe not) But Im just wondering if it could be done...
  16. Sy123

    Quick trigonometry question

    As my math teacher always says, they never give anything in the question in vain.
  17. Sy123

    Polynomials : sum of 2 roots = 0

    I was able to get it using the sum and products of roots rules. I will use roots a, b, c and d because writing alpha in latex is really annoying especially when you have to write ALOT of them. Well here we go. 8x^4-2x^3-27x^2+6x+9=0 \ \ \ \text{Let a, b, c and d be roots to the equation...
  18. Sy123

    Quick trigonometry question

    Draw the triangle, do Pythagoras and you find: \tan{\theta}=\frac{-3}{\sqrt{7}} \ \ \ (\text{Since from}) 90 < \theta < 180 \ \ \ \tan{\theta}<0 \\ \\ \tan{2\theta}=\frac{2\tan{\theta}}{1-\tan^2{\theta}} \\ \\ \tan{2\theta}=\frac{2\times \frac{-3}{\sqrt{7}}}{1-\frac{9}{7}} =...
  19. Sy123

    Year 10 Subject Selection for HSC

    Unfortunately, it makes it less enjoyable. Also, to get into medicine, the minimum requirement is English Standard or above English, so unless you plan on dropping to Fundementals of English, you have nothing to worry about except the UMAT and getting a really really high ATAR. Which is a...
  20. Sy123

    2u maths test

    Also what is the average external marks and external internal marks in your school (just an estimate, to judge difficulty of your school's tests)
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