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  1. Pwnage101

    factorial question

    ^{n}C_{2}+^{n}C_{3}=220 \; \; \; \textup{[Such notation implies}\; n\; \textup{is a non-negative integer (strictly greater than 2), however such knowledge is not requred at HSC level]} \textup{Thus:}\; \; \frac{n!}{2!\left ( n-2 \right )!}+\frac{n!}{3!\left ( n-3 \right )!}=\; \; \frac{n\left (...
  2. Pwnage101

    Titration Q.

    This , however washing the pipette/burette with distilled water THEN the solution they will be filled with is acceptable (and the way i learnt it).
  3. Pwnage101

    help with first order derivative

    \ln \left (AC \right )=\ln \left (C/Q \right )=\ln \left ( C \right )-\ln \left ( Q \right )= \left ( \beta _{1}+\beta _{2}\ln Y_{i}+\beta _{3}\left [ \ln Y_{i} \right ]^{2} \right )-\ln \left ( Q \right )\; \;\therefore \frac{\mathrm{d} }{\mathrm{d} Y_{i}} \ln \left (AC \right )=...
  4. Pwnage101

    upper lower rectangles

    Think about what you are trying to prove, now you have an integral - draw what this means. The integral you have supplied is the area between the curve 1/x and teh x-axis bounded by x=2^n and x=2^n+1 So your 'lower' bound for the integral will be the area of the rectangle with width...
  5. Pwnage101

    multiple chioce question

    According to the 2008 HSC markers (http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2008exams/pdf_doc/chemistry-notes-08.pdf, page 21), either is acceptable.
  6. Pwnage101

    Macq Numeracy Centre

    Yes, for first year MATH and STAT units, they'll help you out. Alternatively, integration/differentiation questions can be posted in the HSC Mathematcs /Extension 1 /Extension 2 forums here on BOS, as long as they are in the correct section. Plenty of people will asnwer your questions :).
  7. Pwnage101

    STAT170 or MATH123

    Well, STAT170 is statistics, whereas MATH123 is the easiest-level Mathematics (i believe its introduction to calculus, so equivalent to 2unit HSC maths). It really depends whether you want to learn calculus or not; if you do, go for MATH123. That being said, some basic calculus may be...
  8. Pwnage101

    How to do well in ECON110?

    Just understand the main concepts / models - Keynesian model, AD-AS model, exchange rate model, etc
  9. Pwnage101

    Chemistry HSC Questions Sorted by Topic

    Re: Chemistry HSC questions sorted topic-by-topic I just found out recently that from 2008 onwards, HSC 'Notes' from the marking centre with the marking guidlines also now come with sample solutions. Looking at the 2008 version (found here, 2009 version has not been released yet), they are...
  10. Pwnage101

    Common cations and annions

    Periodic table will help you out.
  11. Pwnage101

    integration

    let u=secx use the fact that d/dx(secx)=secxtanx
  12. Pwnage101

    Parent Acid and Bases

    In general: Acid + Base ---> water + salt Acid + carbonate base ----> water + CO2 + salt So you may find it useful to work backwards. so, for example, Magnesium Chloride (MgCl2), well this must have been formed from HCl and Mg(OH)2. Sodium Carbonate, well this must have been formed...
  13. Pwnage101

    What is meant by an angle of 75.0° with the vertical.

    Draw a vertical line. A (straight, intersecting) line that is 75 degrees from that. either way.
  14. Pwnage101

    multiple choice questions

    One way to think about it is, it is a dilution by a factor of 10 - we know diluting an acid makes pH increase - pH is a logarithmic scale, so a 10-fold change in concentration means a 1-point change in pH. Thus, pH should increase by 1 - to 2.1+1=3.1. A more rigorous apporach would be as...
  15. Pwnage101

    projectile

    we know 7=Ux*t=U*cos(15)*t---->Ut=7sec(15)...(1) Sy=Uyt+0.5at^2 0=Usin(15)t-4.9*t^2 ---> 0=Ut(sin15)-4.9t^2...(2) we can solve this by substituting (1) in (2) which will leave us with one equation in one unknown: 0=7sec(15)(sin15)-4.9(t^2) 0=7tan15-4.9t^2 solve for t sub back in (1)...
  16. Pwnage101

    Matlab

    The MathWorks Australia - MATLAB and Simulink for Technical Computing Its cheaper than normal if you are a student.
  17. Pwnage101

    Relativistic energy???

    relativistic energy when stationary : E=(m_0)c^2. Realtivistic kinetic energy, as seen by a reference frame in relative motion: KE=0.5(m_v)v^2 your question is vague...
  18. Pwnage101

    resisting g forces

    Sorry, i think the answer is (C), misread the options! From what i remember you always face up - which is the direction of motion during launch, but opposite that during re-entry.
  19. Pwnage101

    Physics Question

    It does not violate the principle of relativity because you have reference to an external point (outside your frame of reference).
  20. Pwnage101

    Molar Ratio of Titration

    1. Find n(NaHCO3) by using n=cv 2. Find n(H2SO4) by dividing n(NaHCO3) by 2 3. Find c(H2SO4) by using c=n/v
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