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  1. Affinity

    best 3u/4u math text book?

    Arnold is good if you bother to learn the concepts. Coroneos if you want some hard questions. If you just want to 'cram' then do papers.
  2. Affinity

    HSC Tips - Harder 3U

    oh.. forgot .. yes you have to prove the cauchy schwarz. what about AM-GM?
  3. Affinity

    How many people are doing 4 Unit

    ask someone smart inthe class or work it out yourself, it's most rewarding the last way
  4. Affinity

    Australian Maths Comp

    q 25) answer is D, 4: let the width of the 18 rectangle be A and that of the 12 triangle be B you can see that the area of the whole rectangle is: (A+B)*(18/A + 12/B) = 30 + 18(B/A) + 12(A/B) >= 30 + 2*sqrt(18*12) by the AM-GM inequality = 30 + sqrt(846) 30^2 = 900 29^2=841...
  5. Affinity

    Australian Maths Comp

    enak, the middle is to be considered also so :P no
  6. Affinity

    Australian Maths Comp

    apologize for the long post, please make corrections as it is likely that I've made mistakes half of this is hindsight wisdom for me q 26) the number is 6037 and that will make the answer 16. start with 10 keep adding 21 until the second condition is satisfied, then add 21*23 until the...
  7. Affinity

    Australian Maths Comp

    the car one should be 6 I think: there are 6 routes from P to Q(satisfying the conditions), count it. you want order reversed so, that means so now two cars can go by the same route. I put down (d)4 yesterday .. hopeless me
  8. Affinity

    Australian Maths Comp

    the answer for the squares one was 4 275 936 184 all sums are 9,10,11 or 12. and we know there are atleast 4 different sums when you consider the middle square and it's 4 sums. Don't ask me how I got that one.
  9. Affinity

    HSC Tips - Harder 3U

    Probability - Get yourself clear about when to add number and when to multiply. You can get probaility involving intervals, not just discrete variables. Inequalities: The cauchy-schwarz inequality is another useful one. (SUM {a<sub>i</sub>b<sub>i</sub> } )<sup>2</sup> <= SUM...
  10. Affinity

    Australian Maths Comp

    here's the proof for it n^12 - n^8 -n^4 -1 = n^8(n^4 - 1) - (N^4 -1) = (n^8 -1)(n^4 -1) = (n^4 + 1)(n^2 + 1)(n+1)(n-1)(n^2+1)(n+1)(n-1) you will have to realise that n^2 + 1, n^4 + 1 are not multiples of 4. (odd^2 is congruent to 1 modulo 4.) or: odd number^2 =(2n+1)^2 = 4n^2...
  11. Affinity

    Uncertainty Principle

    the uncertainty principle only says certain pairs of measurements can never be precise mathematically for any measurements: p*q>h/4PI E*T>h/4PI where p, q, E,T are the uncertainties in momentum, position, energy, time.
  12. Affinity

    Gravitational Constant

    what are the others dubious ones?
  13. Affinity

    Australian Maths Comp

    personally stuffed up big time :P
  14. Affinity

    HSC Tips - Mechanics

    yah unfortunately
  15. Affinity

    bad teacher = bad UAI

    If you can understand what you read on your own(ie. 'outside study' does not mean tutoring), you should well be ahead and what you learn should be much more solid than others. You should inform the principal about your concerns. It doesn't affect you that much since you are first in school...
  16. Affinity

    HSC Tips - Mechanics

    positive and negative are assigned to directions, so if acceleration is considered negative in one direction so is velocity, displacement, forces, etc etc. following that, sometimes you have resistance which is proportional to v^2, and that will complicate things a little when you assign the...
  17. Affinity

    HSC Tips - Mechanics

    It's not that different in maths and physics, just remember to derive your formulae always, leaning physics gives you an edge in this. basics, results that can be used: 1.)change in momentum with respect to time is force: dp/dt = F where p = mv and when m is constant(almost always in...
  18. Affinity

    HSC Tips - Polynomials

    the best preparation for exams is to explain things to others. If you can do it, it means you truely understand the concepts and usually from a variety of aspects
  19. Affinity

    Elementary Particle Dynamics Q

    force due to gravity is mg downwards the component parallel to the plane equals mg*sin(t) where t is the angle of inclination of the plane, show this fact with a diagram. we're told that sin(t) = 1/30 so.. that makes mg/30 yes this is examinable, it's not that hard considering no calculus...
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