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AQA Core 4 MPC4 -- 16th June 2011

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Original post by j04millj
That's what I got too, k=6 ^_^


me tooo :smile:
Dear Readers,

Can you please explain in detail how you did the final 9 mark question? I am totally bemused. I tried to solve it repeatedly but to no avail.

Many thanks,
Lamin Sessay
Reply 122
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DdotT
17
Original post by jesstonto
No :frown: And I'm good at that..


Can't believe something like that wasn't in it, been in 99% of practise papers i've done.... Same with 9 mark Qs, no 9 Mark Questions EVER!
Reply 123
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DdotT
17
Original post by mooser1
2016 I got,it was worded really stupidly but I'm pretty sure that's right.
A=-kt as it was decay.
What about that munter of a question,
2y + (e^2x)y^2 = x^2 + C
What did people get for C? I got 2/e


yep :P 2/e asked couple people they couldn't remember, or maybe we are both wrong?
I got p = 0.5 and q = 2.

Something along the lines of y^0.5 = 2ln(x-1) = x/(x-1)

C worked out to get ln (2x-3) or something (the other ln value) and so it cancelled out with the -ln you got from the integration.
Reply 125
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DdotT
17
Original post by Gen-10
But you were starting it from 1st august 1960, so it works out that 55.33 goes to like december 2015 which means it'll exceed 100'000 on the 1st August 2016 for the first time!


Wasn't the Question asking for which year does it exceed? Not which August of Which year would it exceed.
Reply 126
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j04millj
Original post by DdotT
yep :P 2/e asked couple people they couldn't remember, or maybe we are both wrong?


Well I got e/2 too so unless we're all wrong ... :smile:
Reply 127
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j04millj
Original post by DdotT
Wasn't the Question asking for which year does it exceed? Not which August of Which year would it exceed.


I thought that too. It depends on how the question was worded:
What year did it first exceed 100000?: 2015
Which was the first 1st of August that exceeded 100000?: 2016
Reply 128
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DdotT
17
What did people get for the 7 Mark Question for the Implicit Differentiation? The one after you find C and then after you prove its at a stationary point.
Something like 2x+2y^2e^2x / 2 +2y2e^2x ???
Reply 129
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DdotT
17
Original post by j04millj
I thought that too. It depends on how the question was worded:
What year did it first exceed 100000?: 2015
Which was the first 1st of August that exceeded 100000?: 2016


Something tells me its got to be the first one..
Reply 130
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j04millj
Original post by DdotT
Something tells me its got to be the first one..


Given that I put 2015, it's probably 2016...
The two questions that got me sort of stuck were the vector one and Q8. Hopefully I'll get some method marks even if I don't get the answer right. Hoping for an High B/A
Reply 132
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DdotT
17
Original post by j04millj
Given that I put 2015, it's probably 2016...


i know exactly how you feel, and probs the same for me, coz i put 2015 itll be wrong
Reply 133
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Misiak
did anyone else get their equation as dA/dt = A/(k-t) ?
I somehow didn't notice that we'd just done the partial fraction in part a of Q8 so spent four pages integrating it by parts <_<
Original post by Misiak
did anyone else get their equation as dA/dt = A/(k-t) ?


nah, I got dA/dt = -kA
but the answer was just = -k which is annoying, so I couldn't do part bi :/
Reply 136
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spark343
For the bionomial expansion, it was 1-1/3x-1/9x^2 right? cause the 2nd half of that didn't fit for me, but I couldn't see what I had done wrong ether.
Original post by DdotT
What did people get for the 7 Mark Question for the Implicit Differentiation? The one after you find C and then after you prove its at a stationary point.
Something like 2x+2y^2e^2x / 2 +2y2e^2x ???


Hiya, after differentiating it, i got C = 2/e, but then when you have to prove it was a stationary point, i couldnt get it to = 0. :s-smilie:
Quite a lot of people in my class couldnt either, did anyone actually get it to equal 0??!
Reply 138
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Misiak
Original post by charlotte7474
Hiya, after differentiating it, i got C = 2/e, but then when you have to prove it was a stationary point, i couldnt get it to = 0. :s-smilie:
Quite a lot of people in my class couldnt either, did anyone actually get it to equal 0??!


yeah I did, can't remember what my constant was though
Reply 139
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bish93
Original post by charlotte7474
Hiya, after differentiating it, i got C = 2/e, but then when you have to prove it was a stationary point, i couldnt get it to = 0. :s-smilie:
Quite a lot of people in my class couldnt either, did anyone actually get it to equal 0??!


i couldn't get it to equal 0 either :/
another exam board cock up? or is that just wisful thinking cos i couldnt do it? :P

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