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  1. M

    Section I: Multiple Choice

    Re: Multiple choice answers Yep 14 was A, 15 was C
  2. M

    question - help is appreciated

    i just did 8!/9! number of perms with them sitting opposite / number of total perms
  3. M

    question - help is appreciated

    is the answer 1/9? i'm currently doubting it but meh
  4. M

    Differentiate

    f(x) = x^3 - 3x +4 f'(x) = 3(x^2 - 1) if the curve is decreasing, f'(x) is negative f'(x) is only negative when -1 < x < 1 lol beaten -__-
  5. M

    Quick limit question...

    as x approaches infinity (sinx)/x = 0 but for the question sin(pi/2n) / (pi/2n) as n approaches infinity pi/2n approaches 0 so think of pi/2n as x (sinx)/x = 1 where x is approaching 0
  6. M

    Quick limit question...

    where exactly is sin x/x = 1 as x--> infinity in any textbook. i can only find sin x/x = 0 as x --> infinity according to the "squeeze theorem"
  7. M

    complex number qu

    LHS = | x + yi - i | RHS = y Therefore | x + i(y-1) | = y sqrt(x^2 + (y-1)^2) = | x + i(y-1) | x^2 + (y-1)^2 = y^2 2y = x^2 + 1 y = 1/2 . (x^2 + 1)
  8. M

    Volumes - CSSA 2008 Paper.

    yes, verified it using slices, got the same answer...
  9. M

    Inverse trig. question

    tan-1(4) - tan-1(3/5)= pi/4 tan (tan-1(4) - tan-1(3/5)) = tan (pi/4) RHS = 1 LHS (using double angle formula) = (4 - 3/5) / (1 + 12/5) = 1 LHS = RHS :)
  10. M

    Inverse trig. question

    usually the only thing you have to do is, take tan of both sides and use double angle formula for LHS....
  11. M

    Volumes - CSSA 2008 Paper.

    volume of a shell = 2 pi x y dy so for y = x/2 x = 2y so 2pi (2y^2)dy and for y = sqrtx x = y^2 so 2pi (y^3) dy
  12. M

    Volumes - CSSA 2008 Paper.

    answer is 8pi/3 u^3 if you want to do it via shells rotated around the x axis you have to do shells for y=x/2 minus shells for y = sqrtx V of a shell = 2pi (2y^2 - y^3) dy Integral from 2 to 0 of 2y^2 - y^3 = 2pi [ 2y^3/3 - y^4/4] = 2pi(16/3 - 4) = 8pi/3
  13. M

    Volumes - CSSA 2008 Paper.

    oops made mistake :/
  14. M

    questions - help appreciated

    do you have an actual answer for this, so i can verify if i am right? :)
  15. M

    Scenario: HSC Starts tomorrow?

    Re: HSC Starts tomorrow? I wish the hsc was tomorrow, I've run out of test papers
  16. M

    Complex locus.

    Re: 回复: Re: Complex locus. heres my graph
  17. M

    Rates of Change

    1 cm^3 = 1 milliliter hence C = 8000 not 8 which gives you an answer of 4500mL which = 4.5L
  18. M

    UAI Estimate...

    I'm bored, give me an estimate. English Adv. 130/170 Maths Ext1 62/110 Maths Ext2 45/55 Physics 42/83 Economics 21/40 SDD 2/3 My trial ranks are considerably better than these given overall ranks, because I was gaming too much during terms 1&2 :rolleyes: School is ranked 8th.
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