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AQA Further Pure 2 - Wednesday 18th June 2014

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That was z^4=-9i

I got z=9^(1/4)e^i(kPi/2-Pi/8) for k=0,1,-1 and 2 I think
Reply 61
I got 8cos2θsin2θ=1cos4θ8 \cos^2 \theta \sin^2 \theta = 1 - \cos 4 \theta
Reply 62
Original post by Flauta
I got 8cos2θsin2θ=1cos4θ8 \cos^2 \theta \sin^2 \theta = 1 - \cos 4 \theta


I concur.
Paha i just realised what i did for the final roots of polynomials questions. We had already worked out sum of alpha beta right in part bi or something? Well, i just realised i worked it out again in part c, rather than the sum of roots. I thought it was a bit odd the sum of roots and the sum of alpha beta were the same. :') God i'm a tool.
Reply 64
Original post by Flauta
I got 8cos2θsin2θ=1cos4θ8 \cos^2 \theta \sin^2 \theta = 1 - \cos 4 \theta


I got 1 - (1/2)cos4x somehow
Original post by kingm
I got 1 - (1/2)cos4x somehow


that's what i got.
Original post by ThreePoint14159
That was z^4=-9i

I got z=9^(1/4)e^i(kPi/2-Pi/8) for k=0,1,-1 and 2 I think


I'm pretty sure it was -Pi/4 as the arg. which means instead of Pi/8 it would be Pi/16?
Original post by Sean96H
I concur.


I also concur.
Reply 68
Original post by Ollie_Brown
I'm pretty sure it was -Pi/4 as the arg. which means instead of Pi/8 it would be Pi/16?

I had the arg as -Pi/2
Reply 69
Yuk - what is AQA's problem with their maths papers this year?! :frown: I also got 1 - cos4theta - can anyone remember what the integral was? I think I had pi/3 - (root3)/8??

Also got 5rt2 for last integral, though completely botched up the working.

Differentials of arctans: I integrated then set x=0 so your c comes out as pi/4. Think kind of fudged this though because would only work if you do -c, not +c - is this still ok? :confused:

horrible paper
Original post by Sean96H
I had the arg as -Pi/2


Oh yes, so it would be... Damn, there goes another 5 marks :/
Original post by Ollie_Brown
I'm pretty sure it was -Pi/4 as the arg. which means instead of Pi/8 it would be Pi/16?


Hmm, I got -Pi/2 as the arg in part a), I may well have overlooked something though :/
Reply 72
Was the polynomial something like z^3 + 8z^7 + 7z + 10 = 0 ?
Original post by Vernish
Yuk - what is AQA's problem with their maths papers this year?! :frown: I also got 1 - cos4theta - can anyone remember what the integral was? I think I had pi/3 - (root3)/8??

Also got 5rt2 for last integral, though completely botched up the working.

Differentials of arctans: I integrated then set x=0 so your c comes out as pi/4. Think kind of fudged this though because would only work if you do -c, not +c - is this still ok? :confused:

horrible paper


I got 2Pi/3 + root3/4 for that integral so not sure, but I agree for the last integral :smile:
anyone got the paper/putting together an unofficial mark scheme?
Original post by ThreePoint14159
Hmm, I got -Pi/2 as the arg in part a), I may well have overlooked something though :/


-9i. If you think about it, the arg is definitely (-pi/2). Plot -9i on the graph.
Reply 76
Original post by Vernish
Yuk - what is AQA's problem with their maths papers this year?! :frown: I also got 1 - cos4theta - can anyone remember what the integral was? I think I had pi/3 - (root3)/8??

Also got 5rt2 for last integral, though completely botched up the working.

Differentials of arctans: I integrated then set x=0 so your c comes out as pi/4. Think kind of fudged this though because would only work if you do -c, not +c - is this still ok? :confused:

horrible paper


I got the same for my trig integral I think, my last integral was definitely the same as yours.

I'm sure they'll get the gist of what you've done, integrating was definitely the right step.
Original post by Sayonara
-9i. If you think about it, the arg is definitely (-pi/2). Plot -9i on the graph.


Ah yeah that's a nice quick check, thanks!
Was there anyone who actually found the paper okay (I found it very HARD!)?
Original post by ThreePoint14159
Hmm, I got -Pi/2 as the arg in part a), I may well have overlooked something though :/


Na, dont mind me. I've got it wrong, it should be -Pi/2. We had an hour of people shouting outside the window and got a measly extra 5 minutes. I've lost about 10 marks from ridiculous mistakes :frown:

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