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    HSC Exam Thoughts 2016. Drastically reduced participation?

    I think the website as a whole (not just post-Exam threads) may have declined in popularity drastically over the years. A good resource is Google Trends, which provides data of relative search popularity on Google over time for any phrase you're interested in. The search term "Bored of Studies"...
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    Cosine rule question

    $\noindent Let $\alpha$ be the smallest angle and $\beta$ the largest. The smallest angle is the one opposite the shortest side and the largest angle is the one opposite the longest side. So by the cosine rule, we have$ $$\begin{align*}\cos \alpha &= \frac{16^{2} + 19^{2} -5^{2}}{2\times...
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    trig equations please show all working especially part a

    $\noindent a) Since $\cot \theta = \frac{\cos \theta}{\sin \theta}$, we have $\cot \theta = 0$ iff $\cos \theta = 0$, which is when $\theta = \frac{\pi}{2} + n\pi$, for some $n\in \mathbb{Z}$.$ $\noindent b) Either $\sin \theta = 0$ or $\cos \theta = \frac{1}{2}$. The former equation has...
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    Integration

    $\noindent For the first one, let $I = \int \frac{3x^{3} - 2}{x^{2} + 4}\, \mathrm{d}x$. Then$ $$\begin{align*}I &= 3\int \frac{x^{3}}{x^{2} + 4}\, \mathrm{d}x - \int \frac{2}{4 + x^{2}}\, \mathrm{d}x \\ \Rightarrow I &= 3\int \frac{x^{3}}{x^{2} + 4}\, \mathrm{d}x - \tan^{-1}...
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    Discussion Thread for Atar Notes & other forums

    Re: ATAR Notes vs Bored of Studies Wow, that is a lot of online users (on ATAR Notes). It does seem to be their highest ever though so far. Do you think it'll continue to increase? They do cater for other states as well though, so maybe that boosts their usage?
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    2 Unit Locus Questions

    Note that for the second question, it is a hyperbola (with eccentricity 2), and its equation can be written in the form ((x – h)^2)/(A^2) – ((y – k)^2)/(B^2) = 1, where (h, k) is where the hyperbola is "centred". Since 4U students study conics, they should be able to get this answer and bypass a...
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    2 Unit Locus Questions

    In fact, since the line y = -1 is a line of the form y = const., we can immediately write down the distance of P(x, y) to this line as being |y+1| without need for calculation. (In general, distance of P(x, y) to the line y = C would be |y – C|.)
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    TSFX Summer School Sydney (@USYD) Yay or Nay???

    Its name is pretty much taboo on BOS (has been for a long time I think), reason being (I'm guessing) that it's a sort of rival site to BOS.
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    Help-marking in chemistry?

    Did you ask your teacher why you've been losing marks for such apparently trivial things?
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    Help-marking in chemistry?

    They can probably find out your name from your student number without needing to memorise it (probably not supposed to though).
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    Conditioning on a random variable

    Incidentally, here's the course song for Harvard's Stat 110: .
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    Suitable method for Induction

    I guess so, but it's probably safer to use the algebraic method.
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    Suitable method for Induction

    $\noindent Yes pretty much, except you don't need a graph to show $k^{2} > 2k+1$ for $k\geq 4$, it can be shown algebraically: $k^{2} = (k+1)(k-1)+1 > 2k+1$, since $k-1>2$ and $k+1>k$.$
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    Implicit differentiation

    $\noindent Using implicit differentiation / chain rule, differentiating both sides wrt $x$, we have$ $$\begin{align*}y + xy' + \frac{1}{1+\left(x+y\right)^{2}}\cdot \left(1+y'\right) &= 0.\end{align*}$$ $\noindent Note that at $x=0$, we have $y=1$, so at this point (substituting $x =0,y=1$...
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    HSC 2017 MX2 Integration Marathon (archive)

    Re: HSC 4U Integration Marathon 2017 $\noindent Equation $(\star)$ follows from using $\int_{-b}^{b}f(x)\,\mathrm{d}x = \int_{-b}^{b}f(-x)\,\mathrm{d}x$.$ $\noindent To help show $(\star \star)$, recall or prove that $\int_{0}^{\frac{\pi}{2}} \frac{1}{1+\tan^{\alpha}x}\,\mathrm{d}x =...
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    HSC 2017 MX2 Integration Marathon (archive)

    Re: HSC 4U Integration Marathon 2017 $\noindent Another method is as follows (we can replace $2016$ with any non-negative even integer $N$ and $\pi$ in the integrand with any positive real constant $a$, so we will do this). $\noindent Let $I:= \int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}...
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    HSC 2017 MX2 Integration Marathon (archive)

    Re: HSC 4U Integration Marathon 2017 What's your final answer? Can't seem to spot it. Edit: Oh found it.
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    URGENT! Is it possible for me to do medicine?

    You should probably do subjects you think are best for your ATAR if you want to get in to UNSW Medicine.
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    HSC 2017 MX2 Integration Marathon (archive)

    Re: HSC 4U Integration Marathon 2017 This is of course a proof that 22/7 > pi.
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