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  1. R

    Q. Trig and Series

    I think it's right. But I am not very sure. 1/10 + 2/10^2 + 3/10^4+...=8/99
  2. R

    Complex Number Q

    |z^3-z+2|=|z(z-1/z)+2|=2|isin@z^2+1|<=2(|iz^2sin@|+1)<=2(sin@+1)<=4 I am not sure if it is right?
  3. R

    Q. Trig

    Answer: If @=(m+1/2)*pie, m is natural, then k can be any natural number If @=/=(m+1/2)*pie, k*@=m*pie+(-1)^m*(n-1)*@ when m=0, k=n-1
  4. R

    More probability. (Simple?)

    Hi, there. Try this calculation: 4P3(5P5/2-4P4)=864
  5. R

    Question from my trials

    u r right. there r two turning pts, sub them back to the P(x), it must be: P(-4th sqrt(c))*P(4th sqrt(c))<0. So, the answer should be: c>(1/4)^(4/5)
  7. R

    The solution of complex number

    Good question! If u got this question in HSC. Just forgot it and don't waste u time!
  8. R

    Harder Counting -- can someone do this?

    Counting Hi, there. Try this calculation: 4P3(5P5/2-4P4)=864
  9. R

    Simple question(s) that needs an answer

    The scale measures the mass which doesn't change no matter where it is, not weight which is determined by the gravity where it is. Even around the Earth, u will find the weight of object will change due to the position since the Earch is not a real round. If not clear, contact me. If any...
  10. R

    Any harder question?

    Sorry about that! Go to "I want inequality question"
  11. R

    Any harder question?

    If the solution is: c*(x^2-y^2)^2=-4*x^3*y^3 Contact me. I will send u the fully solution. If not, it's appreciated to imform me.
  13. R

    Any harder question?

    Hi there: Find the answer to the thread " I want more inequality question"
  14. R

    I want inequality questons

    Any question? Go to thread " Any hard question"
  15. R

    Any harder question?

    Hi, everyone If u got any hard question. u can post here. I am sure that I can help u and send whole solution to your email. Trust me!
  16. R

    The solution of complex number

    How long can u work this question out? No point, but works! What r u looking for? Not the right solution!
  17. R

    The solution of complex number

    (x+iy)^2=3-4i=(2-i)^2 Therefore: x+iy=(+/-) (2-i)
  19. R

    Solve the complex number_best way

    Qusetion: Hi, friends! Try this question. Find x and y is (x+iy)^2=3-4i where x and y are real number? The best solution is posted on "The solution of complex number". I wish it will save u a lots of time and get right answer without any mistakes. Enjoy!
  20. R

    Complex Roots

    The formula is: cos(-theta)=cos(theta) Don't worry about the value of the theta. That's rules. eg. cos(-220 degree)=cos(220 degree) and cos(-1030 degree)= cos(1030 degree)
  21. R

    What's wrong with my working? (complex no.'s q.)

    The final solutions: x=(+/-)[sqrt(2) +/- 1] since x^2=3 +/- 2sqrt(2)=(sqrt(2) +/- 1)^2 If u don't understand. Call me. 0413 197 399
  22. R

    Polynomial + Compx question

    (x+i)^4=x^4+4ix^3-6x^2-4ix+1 ie: x^4-6x^2+1=0 and x^3-x><0 Solve x^4-6x^2+1=0 x^2=3+/-2*sqrt(2)=[sqrt(2)+/-1]^2 Therefore: x1=sqrt(2)+1 x2=sqrt(2)-1 x3=-sqrt(2)-1 x4=-sqrt(2)+1 If something wrong. Inform me! Thanx!
  23. R

    Q. circular geometry

    This question comes from a book. It is very popular.
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