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  1. xV1P3R

    Roots of unity

    Aren't roots of unity nth roots of 1 and hence not applicable to this question? ie z^n - 1 = 0
  2. xV1P3R

    complex quadratic equation

    Rule is valid when all the coefficients are real. $1-2i is one root of x^2-(3+i)x+k = 0$ \\$You know one of the roots $ \alpha =1-2i \\\sum \alpha =\alpha +\beta =\frac{-b}{a} \\1-2i+\beta =\frac{3+i}{1} \\\beta =2+3i \\\sum \alpha \beta =\frac{c}{a} \\(1-2i)(2+3i)=\frac{k}{1} \\2+3i-4i+6=k \\k=8-i
  3. xV1P3R

    Finding the Cartesian Equation

    x=3+rcos\Theta \\rcos\Theta = x-3 \\r=\frac{x-3}{cos\Theta}-----(1) \\y=-2+rsin\Theta \\$sub (1) into$ \\y=-2+\frac{x-3}{cos\Theta}sin\Theta \\y=-2+tan\Theta(x-3) \\y=tan\Theta(x)-(3tan\Theta+2) So it's linear with gradient tan(theta)
  4. xV1P3R

    Parametrics

    If you have a to be eternally positive, it isn't consistent with the general point on the parabola (2ap,ap²) screwing you over when you have an upside down parabola.
  5. xV1P3R

    Curious.....

    Physics - Jacaranda as a textbook we are issued. Maths - Sometimes Cambridge and Corroneos are also issued in addition to Fitzpatrick. Dotpoint books are sold through the school at the start of each year for Physics and Chemistry.
  6. xV1P3R

    Studying on public transport?

    I go to school on a nearly always empty train, so I take out my folder and organise stuff. Gluing pages in, organising my sheets. All the easy stuff with little mental input.
  7. xV1P3R

    Parametrics

    I thought focal length would be |a| as opposed to a.
  8. xV1P3R

    Parametrics

    a=-1, because you the parabola is in the form x² = 4ay Equating it to your equation, you get a = -1 It's just the normal parabola, flipped along the x-axis
  9. xV1P3R

    inverse TRIG : (

    You could take it as a transformation of y = sqrt(9-x²) which is a semicircle with radius 3. Where y = sqrt(9-x²), there is an asymptote because 1/0 does not exist. But as the semicircle approaches 0, the graph approaches infinity if you see what I mean.
  10. xV1P3R

    Yep Mayers Advanced English Class. Does she have a year 11 class, and are you in it?

    Yep Mayers Advanced English Class. Does she have a year 11 class, and are you in it?
  11. xV1P3R

    Woah that post was ages ago. Lol Thanks, and from reading your posts from the Extension 1 Topic...

    Woah that post was ages ago. Lol Thanks, and from reading your posts from the Extension 1 Topic, I guess, since same school, you are doing Human Condition as well?
  12. xV1P3R

    Integration

    8cos^{4}x-8cos^{2}x+1= \\=8cos^{4}x-4cos^{2}x-4cos^{2}x+1 \\=4cos^{2}x(2cos^{2}x-1)-2(2cos^{2}x-1+1)+1 \\=4cos^{2}xcos2x-2(cos2x+1)+1 \\=4cos^{2}xcos2x-2cos2x-2+1 \\=2cos2x(2cos^{2}x-1)-1 \\=2cos^{2}2x-1 \\=cos4x\\\int 8cos^{4}x-8cos^{2}x+1dx=\\\int cos4x\\=1/4sin4x
  13. xV1P3R

    HELP! Please - Trig Equation

    sin{4t}+\sqrt{3}cos{4t}=0 \\sin{4t}+\sqrt{3}cos{4t}\equiv Rsin(4t +\alpha )$where R\geq 0$ \\sin{4t}+\sqrt{3}cos{4t}=Rsin(4t) cos\alpha +Rcos(4t) sin\alpha \\$Equating both side$ \\Rcos\alpha = 1\Rightarrow cos\alpha = \frac{1}{R} \therefore \alpha $ is in 1st or 4th quadrant$ \\Rsin\alpha =...
  14. xV1P3R

    cyclic quads

    Any 3 vertices forming a triangle lie on a particular circle, so it's nothing special
  15. xV1P3R

    3 Unit Revising Marathon HSC '10

    i) A = 1000(1+0.05)^100 = 131,501.2578 with calculator ii) Let (1+0.05) = 1.05 = i k = 1000 1st Year A = ki 2nd Year A = ((k)i + k)i A = (i + 1)ki 3rd Year A = ((i + 1)ki + k)i A = ((i + 1)i + 1)ki A = (i^2 + i + 1)ki 4th Year A = (((i + 1)i + 1)ki + k)i A = (((i + 1)i + 1)i + 1)ki A = ((i^2 + i...
  16. xV1P3R

    Parametric Problems

    Woops, I was wrong about the x>0, now I'm not too sure. I drew a diagram showing that the chords start when P and Q are the same, and by drawing subsequence chords and tangents, you see the line x-y+a = 0 appearing, but no points for x values past the x value of the tangent
  17. xV1P3R

    Parametric Problems

    e) With the aid of a diagram, carefully explain why the locus of T is not all of the straight line. Draw lines through point (2a,-a) through which the line PQ has to pass. Notice how there are areas where chords don't exist One is when the line is completely vertical (not sure if this has any...
  18. xV1P3R

    Oblique asymptote

    You would do this by long dividing x³ by (x+1), but since I don't know how to type it up here, i'll do it the long way y = x³/(x+1) y = (x³ + x² - x²)/(x+1) y = x² - (x²)/(x+1) y = x² - (x² + x - x)/(x+1) y = x² - x + (x)/(x+1) y = x² - x + (x+1-1)/(x+1) y = x² - x + 1 -...
  19. xV1P3R

    Practical Max/min

    But is it safe to just go to second derivative test, if you get a non-zero leave it at that, if you get a zero, you go to first derivative test.
  20. xV1P3R

    Practical Max/min

    t = 500/v c = 150 + v²/80 Let C be total cost C = c.t (cost/time x time) C = (150 + v²/80)(500/v) C = 75000v^(-1) + 25v/4 dC/dv = -75000v^(-2) + 25/4 For poss SP to occur, dC/dv = 0 -75000v^(-2) + 25/4 = 0 25v²/4 = 75000 v² = 12000 v = 109.5445 (v>0) Therefore SP occurs at v d²C/dv² =...
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