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AH Maths 2006 Exam Post Mortem


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Poll: How many marks (out of 100) do you think you got? (37 member(s) have cast votes)

How many marks (out of 100) do you think you got?

  1. Less than 30 (6 votes [16.22%])

    Percentage of vote: 16.22%

  2. 30-50 (4 votes [10.81%])

    Percentage of vote: 10.81%

  3. 50-60 (5 votes [13.51%])

    Percentage of vote: 13.51%

  4. 60-70 (11 votes [29.73%])

    Percentage of vote: 29.73%

  5. 70-80 (5 votes [13.51%])

    Percentage of vote: 13.51%

  6. 80-90 (2 votes [5.41%])

    Percentage of vote: 5.41%

  7. 90-100 (4 votes [10.81%])

    Percentage of vote: 10.81%

Vote Guests cannot vote

#61 south lanarkshire jag

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Posted 19 May 2006 - 05:54 PM



QUOTE(PinkFloyd @ May 19 2006, 06:52 PM) View Post

Stupid question = do you lose marks for not doing graphs on the graph paper provided?


whose drawing a graph?

i drew a few squiggly lines

#62 Jason Bourne

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Posted 19 May 2006 - 05:54 PM

did anyone get z=0 for the gauss elimination.
Nothing!!!!!!!!

#63 south lanarkshire jag

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Posted 19 May 2006 - 05:56 PM

QUOTE(Jason Bourne @ May 19 2006, 06:41 PM) View Post




The square matrices A and B are such that AB=BA. Prove by induction that

 A^nB=BA^n for all integers n=>1.



since they are square matrices it doesnt matter what way they are so basically its just like any other proof by induction

#64 Jason Bourne

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Posted 19 May 2006 - 05:58 PM

who got T=40 for Q10
Nothing!!!!!!!!

#65 e-unit

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Posted 19 May 2006 - 05:58 PM

QUOTE(marcinkania7 @ May 19 2006, 06:49 PM) View Post

When you get to a certain stage it was like 3(k^2+k) or sth anyway you have to do another proof that k^2+k is divisible by 2, then it works

k^2 + k = k(k+1)

that's two consecutive integers, so one of them is even, so teh whole expression is even. Or you can consider cases of odd and even (i.e. let k=2n and then k=2n+1) and show it that way.

#66 Jason Bourne

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Posted 19 May 2006 - 06:04 PM

For all natural numbers n, prove the following true or false:

 n^3 - n is always divisible by 6
Nothing!!!!!!!!

#67 marcinkania7

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Posted 19 May 2006 - 06:05 PM

QUOTE(e-unit @ May 19 2006, 06:58 PM) View Post

k^2 + k = k(k+1)

that's two consecutive integers, so one of them is even, so teh whole expression is even. Or you can consider cases of odd and even (i.e. let k=2n and then k=2n+1) and show it that way.


Yeah and then the whole thing is divisible by 6 and it turns out that n^3 - n is divisible by 6. I think I had this one in my Maths book..

#68 FcukWIT

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Posted 19 May 2006 - 06:07 PM

QUOTE(Jason Bourne @ May 19 2006, 06:58 PM) View Post

who got T=40 for Q10


I got T= 60

The turning point was a Minimum at T=40. Which means you could increase the Temperature even further (tto the maximum allowed, which was 60) and get better Yeild. (I think)

#69 bigyun

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Posted 19 May 2006 - 06:09 PM

it cums out as n n(n+1)(n-1)

2consecutive numbers meaning divisible by 2
also it it 3 consecutive meaning divisible by 3


cos 2 an 3 are prime it is divisible by 2 an 3

i.e 6

#70 e-unit

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Posted 19 May 2006 - 06:09 PM

QUOTE(Jason Bourne @ May 19 2006, 07:04 PM) View Post

For all natural numbers n, prove the following true or false:

 n^3 - n is always divisible by 6

 n^3 - n = n(n^2-1) = n(n-1)(n+1) = (n-1)n(n+1)
3 consecutive integers. Appeal to theorem that k consecutive integers is divisible by k! or say that one must be divisble by 3 and one must be divisible by 2, therefore whole expression is divisible by 6.

#71 Jason Bourne

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Posted 19 May 2006 - 06:14 PM

QUOTE(e-unit @ May 19 2006, 07:09 PM) View Post

QUOTE(Jason Bourne @ May 19 2006, 07:04 PM) View Post

For all natural numbers n, prove the following true or false:

 n^3 - n is always divisible by 6

 n^3 - n = n(n^2-1) = n(n-1)(n+1) = (n-1)n(n+1)
3 consecutive integers. Appeal to theorem that k consecutive integers is divisible by k! or say that one must be divisble by 3 and one must be divisible by 2, therefore whole expression is divisible by 6.


thanks, i would never have guessed smile.gif

QUOTE(FcukWIT @ May 19 2006, 07:07 PM) View Post

QUOTE(Jason Bourne @ May 19 2006, 06:58 PM) View Post

who got T=40 for Q10


I got T= 60

The turning point was a Minimum at T=40. Which means you could increase the Temperature even further (tto the maximum allowed, which was 60) and get better Yeild. (I think)


i think i totally messed that one up
Nothing!!!!!!!!

#72 bigyun

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Posted 19 May 2006 - 06:15 PM

how did u all do that temperature q?

#73 south lanarkshire jag

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Posted 19 May 2006 - 06:18 PM

i cant remember what my answer was think it was 60

you differentiated the original expression anfd then work out the stationary point and found the maximum that would be taken out ie when it would be most effective

#74 Jason Bourne

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Posted 19 May 2006 - 06:19 PM

Can anyone do the following:

By expressing  y=cot^{-1}x as  x=coty obtain  \frac {dy} {dx} in terms of x
Nothing!!!!!!!!

#75 Pringles

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Posted 19 May 2006 - 06:21 PM

I got t= 20 probs wrong. I differentiated and then got T = 20 and T = 40 where 40 yields a minimum turning point and 20 yields a maximum


#76 Jason Bourne

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Posted 19 May 2006 - 06:23 PM

yeah i got something like that
Nothing!!!!!!!!

#77 bigyun

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Posted 19 May 2006 - 06:26 PM

QUOTE(Jason Bourne @ May 19 2006, 07:23 PM) View Post

yeah i got something like that

bloody hell. its just a higher question then!!!??? i thought i wud be too easy to do that so i differenciated it again lol

#78 Jason Bourne

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Posted 19 May 2006 - 06:29 PM

QUOTE(bigyun @ May 19 2006, 07:26 PM) View Post

QUOTE(Jason Bourne @ May 19 2006, 07:23 PM) View Post

yeah i got something like that

bloody hell. its just a higher question then!!!??? i thought i wud be too easy to do that so i differenciated it again lol


it seemed like a higher question yeah. i dont know what the hell its doinig in the advanced higher
Nothing!!!!!!!!

#79 south lanarkshire jag

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Posted 19 May 2006 - 06:29 PM

i hate this paper

wish we had something along the lines of last year so you at least know if you are in the right area with your answers

#80 Jason Bourne

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Posted 19 May 2006 - 06:31 PM

last years was much easier
Nothing!!!!!!!!





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