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  1. T

    Yr 11 question, trouble drawing diagram. Light.

    Homework Statement A film director films a scene by photographing it in a plane mirror. The distance from the camera to the actor is 12.0m. The perpendicular distance from the camera to the plane of the mirror is 8.0m. The perpendicular distance from the actor to the plane mirror is also...
  2. T

    Falling through walls

    I heard of this theory that says if you lean on a wall for a couple of billion years then at some stage you should fall through it. What's this called? Cheers
  3. T

    Changing or moving magnetic field

    Thanks mate.
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    Homomorphisms and kernals

    Yeah true, so the definition I had must've been for something with identity=0. So is it really what is sent to the identity?
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    Rooted zeroes

    Just had me algebra exam and that was a question! I pretty much put what HallsofIvy said. I asked the lecturer after and he said that zeroes were to do with the function and roots were an algebraic property. cheers
  6. T

    My Algebra Questions

    Nope. Think of x_1 = x ... x_2 = y ... x_3 = z etcetera So yours is just g(x), but for a polynomial g(x_1,x_2)=g(x,y) and could be like x^2-3y-14x^3+37 y^99. Then you switch x and y so give g(y,x)= y^2-3x-14y^3+37 x^99 which is different to g(x,y) so they aren't symmetric.
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    Rooted zeroes

    Thanks. By root I mean (x-3)(x+4)=0 =>x=3,-4. Not square roots or anything. I just remembered something being said like (x-2)^3 has three roots but only 1 x-intercept, and then another question which I can't find seemed to imply it was the same case with zeroes and roots. cheers,
  8. T

    Rooted zeroes

    What's the difference between a zero and a root? cheers.
  9. T

    Vector space

    that's really quite elephant, I mean elegant
  10. T

    Some eigenstuff

    I think he means something like, for matrices A,B A.B=0 But the problem is is A=[1 1] and B= [-10 0] ...... [0 0] ... [ 10 0] but obviously A=0 or B=0 is not necessarily true. Something like that.
  11. T

    Changing or moving magnetic field

    Please will you upload them. cheers
  12. T

    Homomorphisms and kernals

    Isn't the kernel the set of stuff that is sent to 0, not the identity?
  13. T

    What exactly are manifolds?

    What about watching a movie? It's kind of like squashing 3D into a flat screen. Like a backwards manifold. Is there some object that describes that?
  14. T

    Just quickly, what is a generator in a group?

    Just quickly, what is a generator in a group? I have a question: "Give an example of an element in (Z_28,⊕) which is not a generator." Cheers,
  15. T

    2^n Induction

    of course, thanks
  16. T

    2^n Induction

    How can I show that 1+\frac{n}{1!}+\frac{n(n-1)}{2!}+\frac{n(n-1)(n-2)}{3!}+...= 2^{n} This comes from proving that the power set of a set with n elements is 2^{n}. I got so far that nCn+nC(n-1)+ ... = what I have above. Now for the induction... Cheers,
  17. T

    Line Integral

    oh right. that makes more sense. cheers,
  18. T

    Line Integral

    What does line integral really mean, what is it doing? Say you have a function f(x,y,z) and you integrate it w.r.t. arc length along some curve C. Is this like finding the area under C over f? Like if you are walking along C, and the vertical area covered below you is the integral? It's...
  19. T

    Is this solvable

    but not knowing them is obviously more painful.
  20. T

    Standard Deviation

  21. T

    How would you do this integral?

    no can do...
  22. T

    How do you find the derivative of

    No, it's plausible because the slope is flat. What about a linear function, y=mx+c? The slope isn't changing, it's constant...but the deriv isn't 0. So the bit in brackets should say "and the second derivative is the rate of change of slope"
  23. T

    Integrate e^(-r^2)

    how about integrating it wrt x. Easy!
  24. T

    Program where you can write in mathematical formulas

    Maybe Ask The Higher Educated Masters At The Institute of Craziness Alright?
  25. T

    Cross Product

    OK. Thanks
  26. T

    Cross Product

    Why is it possible to take the cross product in only 3 and 7 dimensions?
  27. T

    English math books

    Depends on the country. In Western Australia (math capital of the world), a few textbooks have been written specifically for the syllabus. Calculus by OT Lee and Calculus by AJ Sadler. Find them on eBay. Alternatively, you can do chapter 1 of undergraduate calculus books.
  28. T

    The Millennium problems

    Yeah I did. How about "my whole post can die".
  29. T

    How long does it takes to completely understand a page?

    Nope. Inventing questions is quite good because it makes you think. And you could make a question that is impossible to solve, work out why, and you've learned something new.
  30. T

    The Millennium problems

    Actually he did, so the second part of my post can die.
  31. T

    The Millennium problems

    I swear you are some kind of a joke. He didn't say in detail, so it's a fair call.
  32. T

    How long does it takes to completely understand a page?

    That entire post took me about 45 minutes to read so don't anticipate many responses. Just hit up the exercises in the end of the chapter. Invent some questions. Listen to Pink Floyd and power through it.
  33. T

    Energy functions help./

    pretty sure he doesn't get the concept but he knows how to do it. It's like the derivative wrt x (say) along a curve where z,y are constant. Drawing a picture will make it easy straight away. Think of a solid shape. Chop it into two pieces. The rate of change along the edge is kind of doing a...
  34. T

    Time Required Engineering Studies?

    2 hrs study average
  35. T

    Maths jobs

    I'm from Australia. All advice is good.
  36. T

    Maths jobs

    What sort of jobs could someone get if they got a degree in maths i.e BSc(Pure/Applied Maths)? Apart from being a maths teacher, professor, researcher etc..., but more industry work? Cheers,
  37. T

    Transfer function

    This is for a Signals and Noise unit. Part of this assignment is to calculate the transfer function H(f) of an amplifier and do some stuff. I can do the 'stuff', but can't find H(f) which I need. Homework Statement The circuit is a voltage source (geophone) connected to an amplifier which...
  38. T

    Hush-hush physics

    yeah but you did. this thread is a joke. delete it.
  39. T

    Hush-hush physics

    Sounds like paranoia.
  40. T

    Log of i

    Can you get logarithms of imaginary numbers? The reason I was wondering is because integrating 1/(1+x^2) WRT x. I know the answer is arctan(x), but how about breaking it into partial fractions by doing 1/(1-ix)(1+ix)?
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    Public School vs. Private School

    Of the five universities in Western Australia, one is a private Catholic uni which mostly focuses on Arts, Med, Law and Theology. The others have also the cool stuff like engineering, Phys+Math, Chem dadadadadadada... In terms of how good the unis are in general, the private one (I reckon) is...
  42. T

    Second derivative

    Second derivative is the rate of change of the derivative, i.e "how fast is the gradient changing?". Say the second derivative is 1 at point A and 2 at point B on the same function. Then the gradient (the derivative) is changing faster at point A than point B.
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    Kronecker Delta subscript

    It was in an assignment. I wanted to post the whole question but have no idea how to use latex that well (only basic). If you can get this, it was: Show that: Integrate[e^(ix(m+n)),{x,0,2pi}] = 2pi*delta(m+n) the LHS should vaguely resemble a Mathematica input and the RHS (m+n) should...
  44. T

    Kronecker Delta subscript

    the Kronecker Delta function is What does it mean when the subscript is not i,j but i+j?
  45. T

    Original works

    ISBN 0-141-01878-X on my copy
  46. T

    Expectation prob. Proof

    Sorry, X is non-negative.
  47. T

    Expectation prob. Proof

    Homework Statement Prove that E(X) > a.P(X>a) Homework Equations E(X) is expectation, a is a positive constant and X is the random variable. (Note, > should be 'greater than or equal to' but I'm not too sure how to do it) The Attempt at a Solution Well I can show it easy enough...
  48. T

    Challenged in evaluating this limit.

    Denominator grows WAY faster than the numerator, so in this case it goes to 0