• Congratulations to the Class of 2024 on your results!
    Let us know how you went here
    Got a question about your uni preferences? Ask us here

BOS MX2 Trials discussion thread. (2 Viewers)

barbernator

Active Member
Joined
Sep 13, 2010
Messages
1,439
Gender
Male
HSC
2012
You have something like -|x - y| and when x > y, it becomes -(x - y)
Oh whoops, I was considering Bk and Bk-1 as individual terms, but the x is to the same power so its the one term. sweet thanks :)
 

deswa1

Well-Known Member
Joined
Jul 12, 2011
Messages
2,256
Gender
Male
HSC
2012
It's not that much effort lol. Quickest way to find two remaining roots is to use the relationship between roots and coefficients.
Yeah I know- I didn't think of that in the moment though :( Though were you there when I outlined my solution to finding A(x) and B(x) for Q11? I think that is the most unco solution anyone did in the whole paper. Though I made up for it by getting the whole of Q14 pretty quickly which was good :)
 

alexandred

New Member
Joined
Nov 8, 2011
Messages
29
Gender
Male
HSC
2013
Well, just spend 40 mins getting q8 out, christ. Awesome paper, thanks.
 

Trebla

Administrator
Administrator
Joined
Feb 16, 2005
Messages
8,402
Gender
Male
HSC
2006
Yeah I know- I didn't think of that in the moment though :( Though were you there when I outlined my solution to finding A(x) and B(x) for Q11? I think that is the most unco solution anyone did in the whole paper. Though I made up for it by getting the whole of Q14 pretty quickly which was good :)
Think you mentioned something about multiplying additional functions or whatever.

Carrot is still writing up the full solutions. I'm not sure when he will finish and upload them though
 

AwksPear

New Member
Joined
Sep 26, 2012
Messages
2
Gender
Male
HSC
2012
how do you do Q7....still dont get any of the answers LOL...thanks guys :D
 

deswa1

Well-Known Member
Joined
Jul 12, 2011
Messages
2,256
Gender
Male
HSC
2012
how do you do Q7....still dont get any of the answers LOL...thanks guys :D
There's a few ways. This is how I did it. Note that 4a+4b+4c=4 ->a+b+c=1

Now the largest surface area will come from where all the side lengths are equal (you can prove this but not neccessary for MC). Therefore a=b=c=1/3

Now A=6a^2 =6/9= 2/3
 

AwksPear

New Member
Joined
Sep 26, 2012
Messages
2
Gender
Male
HSC
2012
There's a few ways. This is how I did it. Note that 4a+4b+4c=4 ->a+b+c=1

Now the largest surface area will come from where all the side lengths are equal (you can prove this but not neccessary for MC). Therefore a=b=c=1/3

Now A=6a^2 =6/9= 2/3
LOL right....misinterpreted thought a+b+c=4...yea...thanks (Y)
 

JaySimmo

New Member
Joined
Feb 14, 2012
Messages
7
Gender
Male
HSC
2012
There's a few ways. This is how I did it. Note that 4a+4b+4c=4 ->a+b+c=1

Now the largest surface area will come from where all the side lengths are equal (you can prove this but not neccessary for MC). Therefore a=b=c=1/3

Now A=6a^2 =6/9= 2/3
but if all the sides are equal it is no longer a rectangular prism (as the question specifies)?
 

barbernator

Active Member
Joined
Sep 13, 2010
Messages
1,439
Gender
Male
HSC
2012
Loving 16 c) i) now that I have time to fully comprehend it. Inductive reasoning :)
 

deswa1

Well-Known Member
Joined
Jul 12, 2011
Messages
2,256
Gender
Male
HSC
2012
but if all the sides are equal it is no longer a rectangular prism (as the question specifies)?
A cube is a rectangular prism- specifically a rectangular prism where all the side lengths are equal. Its like a square is still a rectangle
 

barbernator

Active Member
Joined
Sep 13, 2010
Messages
1,439
Gender
Male
HSC
2012
Is it actually doable? I'm still intimidated...
Ive proved all the way up to there so far, except a) lol, and its not too bad. There is a bit of reasoning im not sure about, but otherwise good. but for that one, look at the far RHS of the inequality, and then consider if a0/a1 was the minimum. sub it in and u get a1(a0/a1) = < a0 which is true. So no matter what there must be a minimum value in which that holds, and by inductive reasoning it holds the whole way down the chain.
 
Joined
Sep 20, 2010
Messages
2,225
Gender
Undisclosed
HSC
2012
fuck. No wonder my rectangular prism didn't work. READTHEFKNQUESTION.
 

Trebla

Administrator
Administrator
Joined
Feb 16, 2005
Messages
8,402
Gender
Male
HSC
2006
The solution Q16 is actually not too bad when you think about it. I personally think it is not as difficult as some of the earlier questions.
 

deswa1

Well-Known Member
Joined
Jul 12, 2011
Messages
2,256
Gender
Male
HSC
2012
The solution Q16 is actually not too bad when you think about it. I personally think it is not as difficult as some of the earlier questions.
Really? Maybe it is and we all just ran out of time- I'll take a proper look tomorrow. Personally, I could only get a and b) i) 2,3 by assuming the result we had to prove in 1. Everything else though...
 

barbernator

Active Member
Joined
Sep 13, 2010
Messages
1,439
Gender
Male
HSC
2012
oh and deswa, look at 16 c) ii) possibly the easiest 2 marks in the whole paper (srs) and iii) is exactly the same!!
 
Last edited:

deswa1

Well-Known Member
Joined
Jul 12, 2011
Messages
2,256
Gender
Male
HSC
2012
oh and deswa, look at 16 c) ii) possibly the easiest 2 marks in the whole paper (srs) and iii) is exactly the same!!
Haha effffff. I flicked to the very last part of Q16 just in case there was one of those limits questions or something that you could just read off but obviously there wasn't. If we had noticed those questions though...
 
Joined
Sep 20, 2010
Messages
2,225
Gender
Undisclosed
HSC
2012
I think the scare factor contributed to lots of the freak outs in this paper...haha
 

Users Who Are Viewing This Thread (Users: 0, Guests: 2)

Top