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C3 Maths A2 AQA 2016 (unofficial mark scheme new)

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Original post by Sayless
b) find gg(x) g(x) = 1/x therefore gg(x) = x [2]

I got gg(x) = x^4
as g(x) = 1/x^2

can you double check that one, not sure it's right


i gtthat 2
Original post by matty9
Why sub into that?? The eqn was something like f(x) = sec x + tan x so you had to do (1 / cos x) + (sin x / cos x) right?

What was the question asking; I think I've asked like 1000 times ;c.
How many method marks do you guys think there will be for the 7 mark revolution question and the integration by substitution one? I'm relying on those method marks to carry me to medical school lool
M
Original post by RorMur2992
How many method marks do you guys think there will be for the 7 mark revolution question and the integration by substitution one? I'm relying on those method marks to carry me to medical school lool


The method is probably about 6/7 marks usually. I'm hoping for this too because for the revolution one I realised I had differentiated (ln3x)^2 wrong in the last minute and barely managed to change some of the working but not the answer. However it was really scrawny, do you think i'll get those marks?
Reply 64
Original post by Parhomus
What was the question asking; I think I've asked like 1000 times ;c.


I can't remember myself, sorry :frown: something to do with finding a stationary point in the working though

Original post by RorMur2992
How many method marks do you guys think there will be for the 7 mark revolution question and the integration by substitution one? I'm relying on those method marks to carry me to medical school lool


M1 A1 A1 A1 A1 A1 A1
Original post by Parhomus
M

The method is probably about 6/7 marks usually. I'm hoping for this too because for the revolution one I realised I had differentiated (ln3x)^2 wrong in the last minute and barely managed to change some of the working but not the answer. However it was really scrawny, do you think i'll get those marks?


most likely, AQA examiners are used to this, I did the same on the C1 cylinder question last year and they still managed to mark it even though my answer was above my working out xD
How on earth do you go from sec(x) - tan(x) = -5 to sec(x) + tan(x) = -0.2?! No one in my school, not even the teachers, could work this one out :frown:
Original post by matty9




M1 A1 A1 A1 A1 A1 A1


So I guess it depends at which point in the working out I messed up?
Reply 68
Original post by RorMur2992
So I guess it depends at which point in the working out I messed up?


I was being sarcastic lmao

I see things like B1 B1 M1 A1 A1 M1 A1 in mark schemes so could be something like that
Original post by robzwolf
How on earth do you go from sec(x) - tan(x) = -5 to sec(x) + tan(x) = -0.2?! No one in my school, not even the teachers, could work this one out :frown:


You can do (sec(x)- tan(x)) x ((secx+tanx)/secx+tanx)=-5
Then you get (sec^2x-tan^2x)/secx+tanx =-5
sec^2x-tan^2x=1 so u get 1/(secx+tanx)=-5
So secx+tanx=-1/5
Original post by matty9
I was being sarcastic lmao

I see things like B1 B1 M1 A1 A1 M1 A1 in mark schemes so could be something like that


Don't scare me like that hahaha! Yeah that's what I see a lot but I don't know what the B stands for? Oh well it seems to me from looking at marked papers that AQA examiners use the mark scheme as a guideline to mark it, rather than marking it exactly as the mark scheme says
Original post by Parhomus
You can do (sec(x)- tan(x)) x ((secx+tanx)/secx+tanx)=-5
Then you get (sec^2x-tan^2x)/secx+tanx =-5
sec^2x-tan^2x=1 so u get 1/(secx+tanx)=-5
So secx+tanx=-1/5


Wow, thanks, that's not something I think I'd ever have seen...
Reply 72
Original post by RorMur2992
Don't scare me like that hahaha! Yeah that's what I see a lot but I don't know what the B stands for? Oh well it seems to me from looking at marked papers that AQA examiners use the mark scheme as a guideline to mark it, rather than marking it exactly as the mark scheme says


B1 = independent mark apparently

Spoiler

Original post by robzwolf
Wow, thanks, that's not something I think I'd ever have seen...


Don't worry about it; I think I crossed out about 10 different methods before I figured it out. And for the next part of the question it was even worse. cosx=-5/13 hell no. Worse thing is that it would give you an answer which was the inverse of the ones in the equations if you solved for x and substituted back in. I think I coulda gotten around 70 if I didn't have to spend so much time checking that it was correct because of the stupid curveball.
Does anyone remember what the coordinates where for the tangent (and the triangle that followed)?
I'm just sitting here hoping I got my A* which my teachers expected ;_; I'm pretty sure I somehow messed up the area of the triangle question so i got m and n=3 but must've messed up in one place so I should get around half the marks at least. Im sure I will have lost a mark for the range question because I left it as less than instead of less than or equal to; definitely sure I probably lost around 2 or max 3 marks for not finishing off from sinx=2/3 and I know I left out one of the values for x in the last last question. FEELS BAD MAN.
Original post by -jordan-
Does anyone remember what the coordinates where for the tangent (and the triangle that followed)?


In terms of coords all I can remember is a (1,e^-1) or something like that. D:
I'm pretty sure for all my exams I came out thinking they were hard but not impossible but I think when I realised I messed up the 7 marker I was shaking :C.
Reply 78
Original post by robzwolf
Wow, thanks, that's not something I think I'd ever have seen...


For two marks, it was a lot of work - I think it took nearly a page before I managed to get it.
Original post by aoxa
For two marks, it was a lot of work - I think it took nearly a page before I managed to get it.


Well that's what threw me - time was running short, and for two marks, I thought there must be a much simpler way of doing it than going through lines and lines of working.

But then again, it's only two marks, so missing it out isn't the end of the world.

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