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Oh sorry, I didnt make one thing clear: a + b + c = 3

So i used AM-GM inequality and a + b + c = 3 to get ab + bc + ca \leq 3 and \sqrt{a} + \sqrt{b}+\sqrt{c} \leq 3 Subtracting inequalities is incorrect yeh? What about EQUATING these two?

I dont understand what ur saying lol Having trouble integrating?

re: HSC Chemistry Marathon Archive .

Well in part (iii) You prove that F'(theta) = 0 right? What is the condition when this is true? Use this to find the value of theta

y = (x-1)(x+a) (then find a)

It says to use (iii) to show that F'(theta) = 0 when (theta) = blah It is saying, prove that: F' \left ( \frac{\alpha}{2}+ \frac{\pi}{4}\right ) =0

(i) (1) Your aim is to find a relationship between x and v \ddot{x} = g - rv Remember that \ddot{x} = v\frac{dv}{dx} OR \frac{d0.5v^2}{dx} ? I didnt use dv/dt because it doesn have x I going to use this one: becuase recently, i've liked this one the most v\frac{dv}{dx}= g - rv...

Re: HSC 2013 3U Marathon Thread $ A goat grazes a rectangular paddock 10 metres by 20 metres. It is tethered to the fence at one corner of the paddock by an inextensible rope of length x metres, where 10 $< x < 20$. \\ \\ $ $Show that the goat can graze an area of $A m^2$ where \\ \equation{$ A...

Re: HSC 2013 2U Marathon ignore everything i said, im n00b

$Let $a,b,c $ be positive real numbers with sum 3. Prove that \\ \equation{\sqrt{a} + \sqrt{b}+\sqrt{c} \geq ab + bc + ca} I found this problem a while ago and worked it out but the end step was a bit weird (i'll post it up when i'm done with a some past papers) The question is found here...

Re: HSC 2013 2U Marathon ^U used 3U double angles A hint is to never write a '1' as a '1'

Can you tell me your progress on the question?

Re: HSC 2013 2U Marathon wait..... do u know that \lim_{x \rightarrow 0} \frac{sinx}{x}=1? <--have u learnt this?

Re: HSC 2013 2U Marathon It can be done by 2U methods

Re: HSC 2013 2U Marathon This is a 3U double angle formula, so no marks awarded :P

Re: HSC 2013 2U Marathon ^That question is a challenge Heres one to warm you up! \lim_{x \rightarrow0} \frac{sinx}{\sin(2x)}

I had the same thought of doing that then it becomes a tele... but is can you use the method of partial fractions in 3U?

Are you trying to do part (c) without doing part (b)?

where did you get this question from? (i need to know because i can see a method, but its not 3U)