How did you find this year's C3 (EDEXCEL)

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For 8b I somehow managed to get: pi/2, 3pi/2, 2.82 and 5.961..
because I did

cosx(1+3\dfrac{sinx}{cosx})=0

(lol)
The answers were 2.82 and 5.961.
Would I get the 4 marks? would they ignore the other two? or will I drop a mark?

Original post by TeeEm

Your expert opinion pls? :call2:

Reply 61

Buku

Original post by edothero

For 8b I somehow managed to get: pi/2, 3pi/2, 2.82 and 5.961..
because I did

cosx(1+3\dfrac{sinx}{cosx})=0

(lol)
The answers were 2.82 and 5.961.
Would I get the 4 marks? would they ignore the other two? or will I drop a mark?

You would get B1M1 but no A marks and lose the second B, M or A.

Reply 62

Buku

A good paper, out of personal experience, C3 is the one we all underestimate, trust your maths and you will do well. I can only see lost marks for 1B :tongue:

. FM laziness...

Reply 63

TeeEm

Original post by edothero

Your expert opinion pls? :call2:

depends on what the marking scheme says ...
(maximum possible loss 1 mark for extras)

Reply 64

edothero

Original post by Buku

You would get B1M1 but no A marks and lose the second B, M or A.

You see I was thinking I would get 3 because I had two correct solutions..
What I did technically isn't wrong (I think :s-smilie:

) because if you factorise out cosx from 3sinx+cosx you would get cosx[3(sinx/cosx)+1]..
so cosx=0 and tanx= -1/3..

Reply 65

Buku

Original post by edothero

You see I was thinking I would get 3 because I had two correct solutions..
What I did technically isn't wrong (I think :s-smilie:

) because if you factorise out cosx from 3sinx+cosx you would get cosx[3(sinx/cosx)+1]..
so cosx=0 and tanx= -1/3..

Well, definitely the A mark lost, but the M mark also as it is two marks to correctly factorise and be left with tanx = -1/3 only

I hope you get 3 or even 4, however I doubt it will happen.

Reply 66

edothero

Original post by Buku

Well, definitely the A mark lost, but the M mark also as it is two marks to correctly factorise and be left with tanx = -1/3 only

I hope you get 3 or even 4, however I doubt it will happen.

Don't know what possessed me to factorise out cosx instead of dividing by cosx but we'll see.. I hope I get at least 3 :unimpressed:

Reply 67

WelcomeToJ'sFreakShow

Original post by physicsmaths

My god wow. I have asked Cambridge mathmos who have all agreed with me. TeeEm agrees with me aswell.
It doesn't imply there two values of tanx. It means you take positive root if theta is with a certain range and - if it is within a certain range. Look at the cos graph.
Also say you have cos(135) equals something. If you use cos(x)^2 +sin(x)^2=1 you have to take either the positive root or negative root I will let you decide which one is needed.

Posted from TSR Mobile

OMD chill. Ahh, gawd. I'll just ask my teacher to explain it Monday. It's not about who agrees with you. If my understanding is wrong, I'd like to see how.

Reply 68

username1162972

Original post by ExMus

OMD chill. Ahh, gawd. I'll just ask my teacher to explain it Monday. It's not about who agrees with you. If my understanding is wrong, I'd like to see how.

Lol good chance your teacher wont get it either. I just had to teach my teacher why it is plus and minus.

Posted from TSR Mobile

Reply 69

Zenarthra

my said it was very very very easy.
I looked at the paper and I have to agree.

Reply 70

STATER

Original post by Pyslocke

If you showed that sec (2x) as 1/cos (2x), expanded it, simplified for a common denominator and changed the 1 to sin^2x +cos^2x you would most likely get 3 marks. That's what my teacher said anyway

Yh 3 seems most logical. Thanks.

Reply 71

agressive turtle

I drew instead of the exponential graph a graph of lnx cause I'm a bit of an idiot. I still had the right points at where it crosses the axis and for part b) I drew it correctly for my graph. How many marks out of six do you think I will get?

Reply 72

Rkai01

That proof question though, spent like an age on it and nearly made the same move as last years proof.

Reply 73

BBeyond

Original post by TeeEm

all my students on this paper reported back and I do not know what to make of it ...
one of them which is desperate to get A* thinks that A* will be around 65, another was almost in tears, a third one said it was an ok paper...

How was it for you?

Do you reckon there will be any follow through marks in the range question if you got the diff wrong?

Reply 74

Emmi12345

I found the paper to be challenging compared to the 'average' C3 paper, but it was all manageable nonetheless. No question was completely 'inaccessible' to any student who has studied the entire C3 Edexcel content. If it was my opinion, I would predict standard grade boundaries which are ever so slightly reduced. It required you to think, instead of just mindlessly churning out answers, and that's never a bad thing. :tongue:

Reply 75

BBeyond

Original post by Emmi12345

Arsey thinks the boundaries will be a fair bit lower than standard, as does TeeEm.

Reply 76

TeeEm

Original post by BBeyond

Do you reckon there will be any follow through marks in the range question if you got the diff wrong?

almost certainly if you were attempting to find the stationary points

Reply 77

BBeyond

Original post by TeeEm

almost certainly if you were attempting to find the stationary points

ok that's made me feel better, so I should get around 3/4 marks for finding the stationary points using my wrong cubic?

Reply 78

Emmi12345

Original post by BBeyond

Arsey thinks the boundaries will be a fair bit lower than standard, as does TeeEm.

Yay! I hope so :tongue:

They could well be right. As I said, that is just my opinion and definitely not an accurate prediction or anything like that.
Don't want to get my hopes up though...
(For now I'm going to tell myself the grade boundaries will be sky-high to force me to try extra-extra-hard in C4. :wink: