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Yes You may solve quadratics like i do: 1. Find discriminant (the key of life!) 2. Sub into quadratic formula Most people sub it all in quadratic formula and realise the number under root is -ve and have wasted their time, whereas people who do DELTA first, can move onto the next question

x^2 - x + 2 = 0 Explain why this quadratic is impossible to solve (or impossible to find real roots)

Q1. a = 9 x^2 = 9 x = -3, 3 Now, a = -2 x^2 = -2 x = √-2 Is it possible to square root a negative number? Q2. a = 1, -2 U let a = x^2 - x Since a = 1, -2 Therefore, x^2 - x = 1, -2 x^2 - x = 1 x^2 - x = -2 Solve these 2 quadratics to get ur answer

Re: HSC 2013 4U Marathon 1) i seriously dont know 2) so u are saying this: \left ( \frac{\frac{1}{a}+\frac{1}{b}+\frac{1}{c}-3}{3} \right )^3 \geq \left ( \frac{9-3}{3} \right )^3 ..is wrong? idk man..

re: HSC Chemistry Marathon Archive yes remember to talk about [H+] before talking about pH

Nice avatar

re: HSC Chemistry Marathon Archive Question: EA 0.010 M solution of nitric acid and a 0.14M solution of citric acid both have a pH of 2.0. Briefly explain how it is possible that both of these solutions have the same pH.

Parametrics will always provide you will USEFUL information eg. PQ is a focal chord, prove that ____ = ______ This means when u sub in the focus into chord PQ, it'll satisfy it and thus u will attain a CONDITION such as 'pq = -1' All in all, FIND what they GIVE u

n(Na2SO4) = m/M = 0.045...mol [Na2SO4] = n/v = 0.045.../0.2 = 0.226...M(in volumetric flask) 30ml of this 200ml solution is taken out, concentration remains constant, [Na2SO4] = 0.226...M Since acid and base in 1:1 mole ratio, u can use C1V1 = C2V2 i.e. [Na2SO4] . V(Na2SO4) = [H2SO4] ...

Please check ur chemical equation

Re: HSC 2013 4U Marathon idk i cant see it...

yes u are correct! that was an idiotic proof

I never heard of a 'dipole attraction'

look at the Sy's post above, he made a great solution

it doesnt lol, made a mistake yes i made a mistake haha

Finally after some death a) (a/b) + (b/a) ≥ 2 .........[1] c) (a/b) + (b/c) + (c/d) + (d/a) ≥ 4 Same method as (b), but this time its easier, im gonna use AM-GM inequality on each pair of colours (red and blue) First pair: a/b and b/c (\sqrt{x}-\sqrt{y})^2 \geq 0 \\ ~~~~~~~~~~~\therefore x...

Re: HSC 2013 4U Marathon damnn 7 marks

Re: HSC 2013 4U Marathon \rightarrow \\ (\sqrt{x}-\frac{1}{\sqrt{x}}) \geq 0 \\ ~~~~~\therefore x+\frac{1}{x} \geq 2 \dots [1]\\ \\ (i) LHS = \frac{1}{a}+ \frac{1}{b}+ \frac{1}{c} \\ \\ ~~~~~~~~~~~=(a+b + c)(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}) \\ \\ ~~~~~~~~~~~= 3 + a + \frac{1}{a} + b +...

Re: HSC 2013 2U Marathon \rightarrow \\ \\ $If $y = sin^x(x), \\ \\ ~~~~~~~~~~~~~~~~~~~~~~~~~~$Find $\frac{dy}{dx}

haha