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  1. shaon0

    Very interesting

    No, 0.9 (recurring)=1. Not approaches.
  2. shaon0

    Very interesting

    x-y axis are perpendicular because its easier to find distances between points. And, 0.9 (recurring)=1
  3. shaon0

    Hyperbolic function

    That's how my uni tutor does it. I was going to do that method but it would've been hard to understand without LaTeX. It's analoguous to what Gurmies said.
  4. shaon0

    Hyperbolic function

    Kinda looks like the ellipse equation.
  5. shaon0

    Subbing infinity into limits of an Integral

    Let u=j*4*pi*c-j*2*pi*f y= t: (-inf,inf) (1/4) (e^tu/u) = inf
  6. shaon0

    Hyperbolic function

    Let A=atanh(x) and u=sinhA: sinhA=u sqrt(coshA^2-1)=u coshA=sqrt(u^2+1) u/sqrt(u^2+1)=tanh(A)=x u^2=x^2u^2+x^2 u^2(1-x^2)=x^2 u=x/sqrt(1-x^2) (sinh(atanh(x)))^2=x^2/(1-x^2) Same as above: tanh(A)=u coshA=x sqrt(1+sinh(A)^2)=x sinhA=sqrt(x^2-1) u=tanh(A)=sqrt(x^2-1)/x...
  7. shaon0

    Hard Factorisation Problem

    x^3+5x^2+8x+4 =x^3+x^2+4x^2+8x+4 =x^2(x+1)+4(x^2+2x+1) =x^2(x+1)+4(x+1)^2 =(x+1)(x^2+4x+4) =(x+1)(x+2)^2 Try to use the 8 and 4
  8. shaon0

    Parametrics Question

    y=x^2/8 y'=x/4 At P: y'=p y-2p^2=p(x-4p) y=px-2p^2 Similarly, equ of tangent at Q: y=qx-2q^2 px-2p^2=qx-2q^2 x(p-q)=2(p+q)(p-q) x=2(p+q) => y=2pq For focal chord: pq=-1 as tangents meet at 90 degrees y=-2
  9. shaon0

    Quadratic formula to find complex roots

    z=(-1+-sqrt(1^2-4))/2 =(-1+-isqrt(3))/2
  10. shaon0

    Induction

    Yeah realised that after writing that up. But i don't think it matters. ln(k+1)>ln(k) 1/k+ln(k+1)>ln(k) 1/k>ln(k/(k+1)) 1/k-ln(k/(k+1))>0 1/k+ln(1+(1/k))>0
  11. shaon0

    Induction

    1) I get confused with left and right very often. Sorry it should be RHS. 2) Do you agree that...1/k and ln(k/(k+1)) are positive for all k: k>=1? This can be verified by using the derivative and proving the functions are positive for k>=1 but decreasing. So, 1/k+ln(k/(k+1)) >= 0 [Adding...
  12. shaon0

    Induction

    S(n): 1/n =< (1+...+1/n)-ln(n) Base case is trivial Assume, 1/k =< (1+...+1/k)-ln(k) Let n=k+1: LHS=(1+...+1/k+(1/(k+1)))-ln(k+1) =1/k+ln(k)+1/(k+1)-ln(k+1) =(1/k+1/(k+1))+ln(k/(k+1)) >=1/(k+1) Additionally, 1/k, 1/(k+1) and ln(k/(k+1)) <1 for k<1 Thus, LHS=<1 1/n =<...
  13. shaon0

    How to maximise your maths examination marks: Tips from the HSC Examiners

    Always write your working down. In last year's 4u HSC exam, i only gave the answer using auxillary method for a 4marker but didn't write out the auxillary form ie. sqrt(...) is max value thus, something happens. opposed to full working.
  14. shaon0

    Complex Number Questions

    i) 2p^2=iq ii) 2(p^2-1)=q I might put up working a little later.
  15. shaon0

    Choose between Chemistry, Physics and Economics.

    Schoey93 for "Troll of the Year." HSC Physics is a lot worse than HSC Chem, HSC chem was alright excluding titration practical which was gay because of my pedantic teacher.
  16. shaon0

    integration by substitution

    S (x-2)/sqrt(x+2) dx = S (u^2-4)/sqrt(u^2) 2udu = 2 S (u^2-4) du = 2[(1/3)u^3-4u]+C = 2sqrt(x+2).[(1/3)(x+2)-4]+C Yes, is the answer to your question where applicable
  17. shaon0

    Integration

    Didn't that cancel with the 2udu part?
  18. shaon0

    Integration

    Where?
  19. shaon0

    Sin/Cos Question

    No because -1 =< p =< 1
  20. shaon0

    Sin/Cos Question

    -sqrt(1-p^2)?
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