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  1. J

    De moivre's theorem

    Starts it off differently with: http://imgur.com/xkKGwfx (it continues based off this) I don't really like this approach because of the manipulation from step 4 to 5
  2. J

    De moivre's theorem

    Show that sin^3x(cos^2x) = 1/16 (2sinx +sin3x -sin5x) (using the fact that z + 1/z = 2cosx, and z - 1/z = 2isinx) My approach was to expand LHS into sin^3x (1-sin^2x) = sin^3x - sin^5x = (z - 1/z)^3 - (z - 1/z)^5 (then expand and simplify) Is this a viable method? The suggested...
  3. J

    Integration q

    Y = x^2 + 2x, bounded by x = -1 and x = 2. Using a single intergral results in an incorrect answer. Looks like for every positive parabola with a negative boundary, two integral are required. Any other cases for this?
  4. J

    Integration q

    In what cases is it required to split an integral into seperate components in order to get the appropriate answer. Some questions I find require you to split a single integral into two or more parts. Is there a general case in which this applies?
  5. J

    Complex number qs

    http://m.imgur.com/SeuqmHu Idk what to do for the first one For the second, I used sum of gp, but couldn't get the answer. Answers are 16root2(cos^4(pi/16)) and (1+root2)i respectively *edit - for the second q, mistakenly took n to be 20 instead of 21.
  6. J

    Roots of unity - complex no.

    For the argument component, it is stated that theta = 2kpi / n For example, if z^3 = 1, the arguments are 0, 2pi/3 and 4pi/3 What happens to negative numbers, such as z^3 = -1? Is it the same thing, but for odd numbers such as pi/3 , pi, 5pi/3? Thanks.
  7. J

    Poly question (extension Cambridge q)

    um.. do what carrot wrote. Basically, let alpha = -2, and beta, gamma = A Find sum and product of roots and solve simultaneously
  8. J

    app of calc q

    Whoops, I made a slight error. When i said that your max sp would be the max value within your domain, i was incorrect. In this case, by testing values at the domain, x = 3 has the highest value, because f(3) = 13
  9. J

    app of calc q

    And your max pt will be your max value within the domain
  10. J

    app of calc q

    for a), it is inferred that you find the stat pts. By differentiation, x = +- (root) 2 and y = (approx) -1.66 and 9.66 respectively From here, you can already tell which ones are max and min, but to be sure, you can use the table method to determine the roots. *Note that since it asks to...
  11. J

    app of calc q

    http://imgur.com/iVqgqAj Generally, all 'turning point' questions follow the same process: 1. Differentiate 2. Let the derivative = 0 3. Solve for x 4. Sub x back into f(x) to find the coordinates - If they ask for you to determine the nature, you can use either the table method or the second...
  12. J

    The Global Economy - The World Bank

    In what ways has the World Bank contributed to Globalisation?
  13. J

    Quick question

    Find other angles by separating to individual triangles
  14. J

    Anyone with a >80% chance of 99.95?

    I bet 100 on: faisal mreditor triage
  15. J

    Integration q

    does this law basically state that the derivative of the anti-derivative = function? Could this fact be useful for HSC math? and for what circumstances? thanks.
  16. J

    Integration q

    Hello, I need some guidance with this q http://imgur.com/TtisiTV The algebra is putting me off.
  17. J

    Technique?

    Alliteration, personofication
  18. J

    vertical and horizontal points of inflection

    When y''= 0, you're essentially finding any points of inflexion. I'm not sure where you got the 'vertical' from. Horizontal points of inflexion occur when there is also a stat. pt. at that particular point. That is because the tangent at that point is horizontal.
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