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  1. H

    Prelim Chem Thread

    Hint: find the limiting reagent.
  2. H

    Prelim 2016 Maths Help Thread

    Here is another way to do Q21 Factorise 3 and complete the square, 3x^2 - x + 7 = 3\left( x^2 - \frac{x}{3} + \frac{7}{3} \right) = 3\left( \left(x - \frac{1}{6} \right )^2 + \frac{1}{6^2}+ \frac{7}{3} \right ) The result is clearly positive for all values of x
  3. H

    Physics Help Thread

    Here:
  4. H

    Physics Help Thread

    Yes. Draw a diagram. "Magnitude of displacement" is just the distance between starting point and end point. In this case, it's √2 = 1.4142... ≈ 1.4.
  5. H

    2016ers Chit-Chat Thread

    Portal 1/2 > Challenger
  6. H

    Help wit Q -

    (Another method) The ball being pulled down 2cm from the origin implies that v = 0 at x = 2 or v(2) = 0. So we need an equation relating v and x. Remember that a = -n^2 x , which means n= 16. By chain rule, a = \frac{dv}{dt} = \frac{dv}{dx} \cdot \frac{dx}{dt} = \frac{dv}{dx} \cdot v...
  7. H

    Cambridge Prelim MX1 Textbook Marathon/Q&A

    Re: Year 11 Mathematics 3 Unit Cambridge Question & Answer Thread I'm just looking at the possible ways you can place the Es (or combinations) such that the conditions are satisfied. The placement of the rest of the letters can be ignored since it's all the same for each part of the question
  8. H

    Cambridge Prelim MX1 Textbook Marathon/Q&A

    Re: Year 11 Mathematics 3 Unit Cambridge Question & Answer Thread Did all for fun... but still a bit rusty so it most likely has at least one error ____ We are only concerned on placement of Es so the sample space is \binom{13}{3}. a) Group 3 Es as a blob. There are 11 ways you can place...
  9. H

    Prelim 2016 Maths Help Thread

    x = 0 doesn't work. You are missing something in your solution (-1<x<15/2). Apply what InteGrand said (post #922) and you will get the answer.
  10. H

    Prelim 2016 Maths Help Thread

    Another method is to complete the square: \begin{align*}x(x - 1) &= x^2 - x \\ &= x^2 - 2x + x\\ &= (x-1)^2 -1 + x \\&= (x-1)^2 + (x-1)\end{align*}
  11. H

    Cambridge Prelim MX1 Textbook Marathon/Q&A

    Re: Year 11 Mathematics 3 Unit Cambridge Question & Answer Thread @davidgoes4wce: Out of curiosity, what font is used for the first row of the table and "Total combinations"?
  12. H

    HSC 2016 MX1 Marathon (archive)

    Re: HSC 2016 3U Marathon Here is a hint. Highlight to see. Also in LaTeX code to try to prevent immediate comprehension in-case you accidentally highlighted or ctrl+A ___ \frac{a^{k+1}+b^{k+1}}{2} \geq \frac{a^kb + b^ka}{2} = \boxed{?}\times \left( \frac{a^k + b^k}{2} \right ) + \boxed{?}...
  13. H

    2U/3U Yr11/12 Tutoring | BSc(Advanced Mathematics)/BSc(Computer Science) @ UNSW

    Hey guys, my name is Patrick and I completed the HSC in 2013 achieving a band 6 in 2U and E4s for both 3U and 4U. Reiterating: I'm a third year Advanced Maths/Comp Sci student studying at UNSW and I offer private one-on-one tutoring for 2U and 3U. Aim To give you more confidence when doing...
  14. H

    HSC 2016 MX1 Marathon (archive)

    Re: HSC 2016 3U Marathon Yeah! I made a little typo on the denominator
  15. H

    HSC 2016 MX1 Marathon (archive)

    Re: HSC 2016 3U Marathon Assuming a is A and b is B, could there possibly be a typo in the question? Suppose a = 0.1, b = 0.2 and n = 3. Then \left(\frac{a+b}{2} \right )^2 = \left(\frac{0.1+0.2}{2} \right )^2= 0.0225 \frac{a^n+b^n}{2} = \frac{0.1^3 + 0.2^2}{2} = 0.0205 Therefore...
  16. H

    ngo and sons entrance exam failed

    How long has it been since you did the entrance exam? The mark does not matter if you want to get accepted, it's the last question that matters ^_^
  17. H

    polynomial help

    Do you know a relationship between a polynomial's roots and it's coefficients?
  18. H

    Logs !!! Help

    High chance this person is a female but this is judging from a small population and one person's observation. I noticed that females are more likely to add a "bubbly"-style to their handwriting than males. However, the curvature of the letter "y" and the terminating point of the tail is...
  19. H

    Need help with a math question please (Algebra and surds)

    According to wolframalpha, the answer provided is right
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