ATAR Notes: Forum

VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Mathematical Methods CAS => Topic started by: luken93 on April 16, 2011, 07:23:36 pm

Title: Methods Nifty Tricks/Methods/Solutions!
Post by: luken93 on April 16, 2011, 07:23:36 pm: I want to compile a thread of any smart (or as ATAR would say, sexy :P ) methods to solving answers.

I've noticed some over the last few weeks on here, such as the domain of composite/product/addition is the intersection of the two functions, that sort of thing. (Can't remember this one exactly, so if it's you post it up!)

So if anyone has any that they come across in their workings, then put them up here if you can :)

Also, if you want to show an example it'll probably save the hassle of explaining it later...

Hopefully this works out, and thanks in advance!
Title: Re: Methods Nifty Tricks/Methods/Solutions!
Post by: Water on April 16, 2011, 07:27:03 pm: Hey Luken93 xD, not sure if this is a smart working ot, but as I was doing this problem, I thought that many students might use derivative or what to figure out this question, even though it looks so complex. But Rather its super simple.

A probability model for the mass x kg of a 2 - year - old child is given by

f(x) pie/20 sin [ pie/10 ( x- 7) ] 7 < equal x < equal 17.

a) Find the mode of X, M.

You don't need to find the derivative as the book says.

Simply

You equate

pie/10 ( x- 7) = pie/ 2

x - 7 = 5

x = 12

x = 12 is your mode for X.

You can remove it if you want, not sure, if its smart or whatever lol. Just came across my mind when I was doing it, that alot of people might use derivative >:!
Title: Re: Methods Nifty Tricks/Methods/Solutions!
Post by: iNerd on April 16, 2011, 07:30:21 pm: Quote from: luken93 on April 16, 2011, 07:23:36 pm
I want to compile a thread of any smart (or as ATAR would say, sexy :P ) methods to solving answers.
You know me well. That was amusing :P

Only nifty trick I can offer is to sleep a good 9 hours before your Methods exam to counter sleep deprivation effects ;)
Title: Re: Methods Nifty Tricks/Methods/Solutions!
Post by: pi on April 16, 2011, 08:14:22 pm: Does everyone know that it is actually 'pi' and not 'pie'? :P
Title: Re: Methods Nifty Tricks/Methods/Solutions!
Post by: Water on April 16, 2011, 08:15:05 pm: DannyN, the equation is at it stands lol. Nothing incorrect, besides pi's pi and pies. pi, the Pi Master.

Moderator action: removed real name, sorry for the inconvenience
Title: Re: Methods Nifty Tricks/Methods/Solutions!
Post by: DannyN on April 16, 2011, 08:18:55 pm: woops my bad :P
i see your reasoning ^^ havent done methods for a while :P
Title: Re: Methods Nifty Tricks/Methods/Solutions!
Post by: luken93 on April 16, 2011, 08:19:38 pm: Quote from: pi on April 16, 2011, 08:14:22 pm
Does everyone know that it is actually 'pi' and not 'pie'? :P
pi, wasn't it you that stated something about the domain being the intersection of two functions? Which did it apply for?

@Water, I assume what you are doing is finding the max of the sin graph, which is essentially the turning point and mode?
Nonetheless, takes out the middle step of finding the turning point!

Moderator action: removed real name, sorry for the inconvenience
Title: Re: Methods Nifty Tricks/Methods/Solutions!
Post by: pi on April 16, 2011, 08:22:37 pm: Quote from: luken93 on April 16, 2011, 08:19:38 pm
Quote from: pi on April 16, 2011, 08:14:22 pm
Does everyone know that it is actually 'pi' and not 'pie'? :P
pi, wasn't it you that stated something about the domain being the intersection of two functions? Which did it apply for?

You mean in this post?
Quote from: pi on March 13, 2011, 02:55:04 pm
$Let \ f(x) = \sqrt{x +3} \ and \ g(x)=\frac{x}{\sqrt{2x - 1}}$
$Domf \ \cap \ Domg$
$[-3, \infty ) \ \cap \ ( \frac{1}{2}, \infty)$
$Dom=( \frac{1}{2}, \infty)$

That rule is for addition/subtraction/product functions, pretty nifty I guess

Moderator action: removed real name, sorry for the inconvenience