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# Official Edexcel C3 Discussion Thread watch

1. There's an unoffical markscheme on here, has anyone checked their answers?

I got a B according to it, made some errors but meh..
2. hey i got sum answers :>

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this is the one with the minimum (a,b) and you have to find a and b, did anyone get the same as me?

so a = -0.196

then put x = -0.196 into the original equation to find b = 0.812
3. (Original post by Arsey)
Very hard I thought. Here are my solutions (updated!)

Thanks a million I was panacking about how I done but you've put my mind at rest, cheers
4. (Original post by Remarqable M)
i said fg(x)>4 would i still get mark? i wasn't too bothered about finding domain and range question.
no
5. (Original post by Casshern1456)
There's an unoffical markscheme on here, has anyone checked their answers?

I got a B according to it, made some errors but meh..
where's the unofficial markscheme? :O
6. i got that answer for A and B but seriously it didnt look right. can you tell me where this unofficial mark scheme is ?
7. (Original post by relentless_wind)
where's the unofficial markscheme? :O
http://www.thestudentroom.co.uk/atta...5&d=1264067467 - Thanks to Arsey

Edit: See this thread for more discussion: http://www.thestudentroom.co.uk/show....php?t=1158161
8. (Original post by Anonymous0155)
i think for 9bii) it was x2 - 2x + 4. differentiate and its 2x = 2, x = 1 as the minimum. so i had the range as fg(x) >= 1

i dont think the range would be x>3 as the (x-1)^2 wouldnt be x>0
yes, but.... x=1 is the x-coordinate of the minimum point; the range refers to the minimum y value in this case.
9. (Original post by craglyboy)
Thanks for the clarification i still cant believe how well some people presume they have done lol why are they doing retakes :P
For the A*. I was retaking C3 yesterday and I scored 88 last summer
10. (Original post by klgyal)
never 100%; I am only human.
11. (Original post by xSkyFire)
Why don't all of you people rep Arsey, he does solutions and clarifies questions and gives grade boundary advice. Not even my own tutor does that (not without hassle from everyone else), AND I PAY HIM u___u
that is a very kind post; however, I have absolutely no idea what all this rep business is about. Just trying to help and I also benefit from learning from your experiences of the paper(s).
12. (Original post by john1234567)
i love it when people don't recognise the difference of two squares
I know, it was so simple
its always the simple things

And for question 8
I overlooked cot(2x) = cos(2x)/sin(2x)
and thought 1/tan(2x) doesnt give any solutions
so i only gave the 2 from the inside bracket
>.<

definitely resitting in june
because looking through it there was nothing hard, it was just stupid mistakes on my part
13. Man, it was awful.
I'd swear the only questions that I've answered every part of are the Rcos one, the iteration one and the composite functions one!
Hopefully as we all found it hard though they'll lower the boundaries?
As long as there weren't loads of people who cheated by calling like those further up, that is! ^
Hmmm. Either way, definitely kissed goodbye to an A there! Probably to the B too.
14. (Original post by Arsey)
that is a very kind post; however, I have absolutely no idea what all this rep business is about. Just trying to help and I also benefit from learning from your experiences of the paper(s).
Indeed, much obliged sir.
15. (Original post by Arsey)
nah, you are wrong.

in fg(x) the range of g(x) becomes the domain for f(x) in the composite function

f(x) = e^2x + 3 this has an asymptote at y=3 thus can not be equal to 3. Therefore the range of fg(x) > 3 NOT >=

if fg(x) = (x-1)^2 + 3, where whatever g(x) is the input, and that g(x) can equal 1, such that fg(x) = 3.

And surely if the range of g(x) which includes 1, becomes the domain of f(x) in the composite function, as you claim, then fg(x) = 3 is a plausible argument. Basically, that just validates my point.
16. (Original post by Arsey)
that is a very kind post; however, I have absolutely no idea what all this rep business is about. Just trying to help and I also benefit from learning from your experiences of the paper(s).
i got only 2 solutions for Q8(22.5, 112.5). my range for Q9(last part was wrong)
by mistake i differentiated the ln question as 1/x^2 x 2x instead of 1/x^2+1 x 2x. hence my final answer is wrong.
so i am guesssing about 5 marks off. how much UMS could that be?
17. (Original post by Elitist1991)

if fg(x) = (x-1)^2 + 3, where whatever g(x) is the input, and that g(x) can equal 1, such that fg(x) = 3.

And surely if the range of g(x) which includes 1, becomes the domain of f(x) in the composite function, as you claim, then fg(x) = 3 is a plausible argument. Basically, that just validates my point.
DOMAIN OF G(X) IS X>1
18. (Original post by Doughboy)
You could have done it that way.

Even though it specifically asked for it in the form 1/cos x?
19. i might get 67/75 approximately how much will it be in UMS
20. yes, it doesnt matter cosx^-1 is the same as 1/cosx

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