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  1. fan96

    Conflict in General Maths HSC paper 2018!?!

    Your answer doesn't work for the second equation: 3(3)-(-2) = 9 + 2 = 11 \neq 7.
  2. fan96

    Cambridge Prelim MX1 Textbook Marathon/Q&A

    \frac{1+\sqrt{1+\frac{\sqrt{3}}2}}{\sqrt{1+\frac{\sqrt{3}}2}} \cdot \frac 22 = \frac{2+\sqrt{4+2\sqrt3}}{\sqrt{4+2\sqrt3}} = \frac{3 + \sqrt3}{\sqrt 3 + 1} = \frac{\sqrt 3 (\sqrt3+1)}{\sqrt 3 + 1} = {\sqrt 3}
  3. fan96

    Weird circle

  4. fan96

    Inverse Trig and Identities Questions

    ii) The line through AP has equation y = t(x+1) . (can you see why?) Solve this simultaneously with the equation for the unit circle to obtain a quadratic in x : (1+t^2)x^2+(2t^2)x+(t^2-1)=0 This equation tells us where the line intersects the circle. You could just throw the quadratic...
  5. fan96

    MX2 Integration Marathon

    For k > 0, \, n \in \mathbb{Z}^+, let I_n = \int x^k (\log x)^n \, dx. Prove that (k+1) I_n = {x^{k+1}(\log x)^n} - {n}I_{n-1}. Given that \lim_{x \to 0} x^k (\log x)^n = 0, Show that \int_0^1 x^k (\log x)^n \, dx= (-1)^n \frac{n!}{(k+1)^{n+1}}, \frac 1 e \int_0^e (\log x)^n \, dx =...
  6. fan96

    Weird circle

    Construct lines to the centre from each intersection point. This forms sectors of isosceles triangles. Because equal arcs of a circle subtend equal angles at the centre, you can find all the angles in each sector. Then solving for x should be easy. I believe the answer should be 60^\circ.
  7. fan96

    Volume Integration Question !!!!

    The standard formula for volumes of solids with similar cross-sections is V = \pi \int_a^b r^2\, dh (in this case, r = y, \,\,h=x) This can be thought of as approximating the volume of the solid with several cylindrical slices, and then making these slices thinner and thinner. The volume of...
  8. fan96

    Term 1 2019 Results Discussion Thread

    Not really, my team was great and it was really nice working with them. It was mostly due to: - our robot's parts being poor quality and some failing on us in final testing - bad marks on individually submitted reports, no feedback was given (having them squished in the last two weeks of term...
  9. fan96

    Term 1 2019 Results Discussion Thread

    ======================================================== T1 COMP1511 Programming Fundamentals.........95 HD T1 ENGG1000 Engineering Design...............64 PS T1 MATH1141 Higher Mathematics 1A............99 HD ======================================================== Term WAM...
  10. fan96

    Term 1 2019 Results Discussion Thread

    getting a 99 in math1141 was a really pleasant surprise... was expecting somewhere around 80-90.
  11. fan96

    Help with trig proof and limit question??

    Note that before we do anything else, b must be nonzero. Also, to apply the identity we require 1 + \cos ax \neq 0 \iff ax \neq \pm\pi, \, \pm 3\pi ... One method is \begin{aligned} & \frac{1 - \cos ax}{bx} \\ &= \frac{\sin^2ax}{bx(1+\cos ax)} \\ &= \frac{4...
  12. fan96

    JRAHS 3U 2007 Trial Poly Question

    Let P(x) = ax^3+bx^2+cx+d . Because P is odd, P(x) = -P(-x) and therefore b = d = 0 . P(x) = ax^3+cx . By the remainder theorem, P(-4) = 0 and P(3) = 21 . Performing substitutions, we obtain \begin{cases}16a + c &= 0 \\ 9a + c &= 7 \end{cases} \implies a= -1,\, c =16
  13. fan96

    parametrics question

    Here's another solution: \begin{aligned} \frac{y-x}{x+y} &= \cos \theta \\ 1 - \left(\frac{y-x}{x+y}\right)^2 &=\left(\frac{y-x}{2}\right)^2 \\ (x+y)^2- (y-x)^2 &= \frac 1 4 (y-x)^2(x+y)^2 \\ 16xy &= (x^2-y^2)^2 \end{aligned} i.e. (x^2-y^2)^2-16xy=0 It's also clear to see solving this...
  14. fan96

    Binomial Theorem Question

    Firstly, (2-x)^n = \sum_{k=0}^n \binom{n}{k} 2^{n-k} (-x)^k Set k = 2, 3, giving the coefficients of x^2 and x^3 : \binom{n}{2} 2^{n-2} (-1)^2 and \binom{n}{3} 2^{n-3} (-1)^3 Now all you need to do is to solve \binom{n}{2} 2^{n-2} (-1)^2 = - \left(\binom{n}{3}...
  15. fan96

    MX2 Integration Marathon

    I = \int^{\pi/3}_{\pi/6} \frac{\tan^4x+\cot^4x}{1+\tan^{\frac{2019}{2020}}x} \,dx First we note that (\tan x)^{-1} = \cot x for x\in [\pi/3, \, \pi/6] . Using \int_a^{b} f(x) \, dx =\int_a^{b} f(a+b-x) \, dx , \tan(\pi/2 - x) = \cot x , and \cot(\pi/2 - x) = \tan x...
  16. fan96

    MX2 Integration Marathon

    Re: HSC 2018 MX2 Integration Marathon Hint: \sqrt{x^2} = |x|
  17. fan96

    Triangular Number Sequence

    i.e. "count all the rows before, and add a new row". The algorithm could look like: BEGIN total = 0 FOR row = 1 TO 10 STEP 1 total = total + row Display total NEXT i END Specifically, look at this line: total = total + row In total + row, total...
  18. fan96

    Algorithm in Visual Basic

    your pseudocode is logically correct (if you intended the "count+1" to be outside of the IF statement) but you have some syntax errors. BEGIN count = 0 present = 0 GET advent WHILE advent has not ended IF advent[count] = "Present" THEN present =...
  19. fan96

    MX2 Marathon

    Re: HSC 2018 MX2 Marathon The equation of the tangent at the hyperbola is given by y-a\tan\theta = \csc \theta(x-a\sec\theta) Because the shortest distance between a point and a line is the perpendicular distance, M is the intersection between the tangent line and the line perpendicular...
  20. fan96

    How much time should I put into studying for 3u?

    Sure, feel free to PM me. (the same applies to anyone else reading this who wants help)
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