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  1. who_loves_maths

    Int. Help

    Hi sasquatch, (16 - x2)/x2 = 16/x2 - 1 Therefore: ∫(16 - x2)/x2 dx = ∫16/x2 dx - ∫1 dx = -16/x - x + C Hope that helps. P.S. Riviet how can you just jump to the conclusion that he's looking for a more advanced technique? Maybe there are people out there who are genuinely...
  2. who_loves_maths

    projectile motion harder problems

    Thank you shsshs. Unfortunately, nice but not great.
  3. who_loves_maths

    projectile motion harder problems

    Hi shsshs, Question 1a): i) Both parts a) and b) involve statements about the velocity(remember vectors: directions as well) of the projectile at point of contact. A natural question would then be "what is mathematically related to the direction/angle of velocity"? A: The gradient of the...
  4. who_loves_maths

    Integration of Logs HELP

    Hey sando, Question 1: The equation of interest is ln(x) = y ---> x = ey , because you will be integrating with respect to dy: I = {4 -> 2}∫ey dy = [ey]{4 -> 2} = e4 - e2 = e2(e2 - 1) units2 Question 2: Once again, the equation of interest is x = ey for the same above reason...
  5. who_loves_maths

    Another Conics question.

    ? Umm... unfortunately no McSo, since the condition that the tangent be perpendicular to PQ is exactly what you are trying to find in the first place! But of course once you have shown that, then a simple geometric argument following that will suffice towards the final proof. (i.e. that...
  6. who_loves_maths

    Another Conics question.

    This is why "rough" sketches are dangerous in maths... The reason you think the normal is perpendicular to PQ is most probably because you are drawing the three points P, Q, R on the same branch of the hyperbola Riviet. This cannot happen, as you will see with a more accurate diagram. The...
  7. who_loves_maths

    Another Conics question.

    Looks like the normal is fine from here Riviet.
  8. who_loves_maths

    Sum Of A G.p.

    Don't stress out about G.P.'s ppl, after all, the greatest French mathematician (and generally the greatest intuitionist) of all time Henri Poincare did not even know how to prove the formula for the sum of a G.P. during a matriculation exam! (of course, he was under pressure from being late...
  9. who_loves_maths

    Integration of Logs

    Hey, Divide the 'x' throughout each term of the numerator: ie. (2x³ - x² + 5x + 3)/x = 2x³/x - x²/x + 5x/x + 3/x = 2x2 - x + 5 + 3/x And so: I = {2 -> 1}∫(2x³ - x² + 5x + 3)/x dx = ∫2x2 dx - ∫x dx + ∫5 dx + ∫3/x dx = (2/3)[x3]{2 ->1} - (1/2)[x2]{2 ->1} + 5[x]{2 ->1} + 3[ln(x)]{2...
  10. who_loves_maths

    Induction.

    The Principle of Mathematical Induction (both the weak and strong version, coupled with other techniques oftened called "backward induction") is a principle in mathematics used often to prove mathematical statements that generalise into an infinite class/family of numbers. It is a principle that...
  11. who_loves_maths

    Application of Calculus In the real world Q's

    Part a) {apologies for my poor illustration skills...} Part b) Differentiate the expression with respect to t to obtain velocity v = dx/dt: v = dx/dt = 4Sin(2t) Rest means v = 0: 0 = 4Sin(2t) = Sin(2t) -----> t = (1/2)k.pi ; where k is a nonnegative integer and "pi" is your...
  12. who_loves_maths

    OH NO my calculator DIED!!!!

    Thanks for correctin' the record Kidmin ;)
  13. who_loves_maths

    OH NO my calculator DIED!!!!

    As Kid.@dmin has said him/herself which you quoted: "...shall results in a very... stupid me." It wasn't necessary that you paid reminder to the stupidity part again... wasn't very nice now was it? Anyways, back to the original discussion on calculators... isn't it a shame that it's become...
  14. who_loves_maths

    honours in science at anu

    though admittedly, one wouldn't consciously choose ANU for that particular field of study as an undergraduate unless one did not have a choice... (if you are interested in immunology, pathology, and/or microbiology, take a look at UM or UQ as well.)
  15. who_loves_maths

    honours in science at anu

    'tis indeed false. usually, honours are offered in every discipline for which a major may be obtained in the (usually) three years prior to the 4th.
  16. who_loves_maths

    imo 2006

    ^ Yes, that's the Frank I was talking about - we're in the same class (you're in it too aren't you?). Btw, best of luck with your 2301 exam on Thursday Steele :) . (and all your other exams also)
  17. who_loves_maths

    imo 2006

    ^ ? no unfortunately, though I do know Frank (from the same school as Vinh right?) :) .
  18. who_loves_maths

    Name of this proof

    Hi ... , hope this is still in time to be of some help to you. From what I can see, there are three ways of (formally) solving this problem: 1) Calculus, 2) Geometry, or 3) Inequalities; all of them beyond HS level mathematics. Since in mathematics any geometrical solution is usually the...
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