C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST

Ahh - I did the correct working out initially for Q3, got the differentiation correct but when working out x, I got up to -1/9pi and I was going to change it - but then at the end moment, I crossed my initial working out, put a cross in it and did some other working out. The work out with a cross in it was still readable. I know it's highly unlikely, but will I still get marks for this?

Also for 3tan2y differentiated in terms of x, I left it as

1/6+6(x/3)^2, I didn't simplify it fully in the end, will I lose a final accuracy mark?

(edited 11 years ago)

Reply 181

raheem94

13

Original post by sweetascandy

ARSEEEYYYY, I know this isn't the right thread for this, but can you pleeeeeease post an m3 mark scheme on the m3 thread :please:

He doesn't do M3 solutions and he has also gone offline.

Gibbo81 does them, but i think he isn't doing it this time.

Btw, i didn't gave you the neg rep.

Reply 182

Gman1234

6

Hard paper :/
52/75 for me :frown:

Need 60ums on c4 for the friggin A now!

Reply 183

mishmash67

5

i messed up on question 5 only got part c and then 8b i didnt get all the solutions :frown:

but alot better than i had originally thought

Reply 184

joneasy

Original post by The_Pen

I solved that by using the R sin(3x+a) identity and got the same answer as Arsey. I hope I won't get penalised.

You could write it as that.

right if you could right it as that then could you set cos3x = 0 then get an answer from that??

Reply 185

joneasy

Original post by 0range

It would only be (3 + √3tan3x) = 0

Idk if you would lose any marks though

why could you not use the other one?

Reply 186

Umby

I got everythign correct except 7 b) I only got to dy/dx = cos^2(arctan x/3)

Its a 5 marker anybody reckon I will have got more than 2 marks, maybe 3 for working? I NEED an A* so incredibly badly.

Reply 187

sweetascandy

18

Original post by raheem94

He doesn't do M3 solutions and he has also gone offline.

Gibbo81 does them, but i think he isn't doing it this time.

Btw, i didn't gave you the neg rep.

Ohhh

Okay, well thanks for telling me! :redface:

Reply 188

jmalks

1

I know this is an essay but pleeease help :smile:

7 b) I got an equal answer to the mark scheme just less simplified using a different method. It's an essay but help meplease :P I said dy/dx=(1/6)cos^2(2y) then x/3=tan(2y) and drew a triangle with the angle=2y and the opposite=x and the adjacent=3. Then I worked out the hypotenuous using pythagoras as (x^2+9)^(1/2) so I said x=(x^2+9)^(1/2)sin(2y). I then rearranged dy/dx so it equalled (1/6)(1-sin^2(2y)). From my triangle I could work out what sin^2(2y) is in terms of x and find dy/dx like that. I got the answer as (1/6)(1-(x^2/(x^2+9)) which is the same as the answer just less simplified. Would I lose marks?? Thank you

Reply 189

0range

20

Original post by joneasy

why could you not use the other one?

Honestly Idk!! ask Raheem he's a genius at this stuff!

Reply 190

raheem94

13

Original post by 0range

Honestly Idk!! ask Raheem he's a genius at this stuff!

lol

Which question are talking about?

Reply 191

masr123

why are you losers asking eachother questions? there's a markscheme, check the answers and then wait for your results, don't keep asking stupid question, idiot.

Reply 192

0range

20

Original post by raheem94

lol

Which question are talking about?

Original post by joneasy

yea but like you divided by cos3x so whenever we had
3cos3x + √3sin3x = 0

could you not rewrite that as
cos3x ( 3 + √3tan3x) = 0

if not why not

Reply 193

kpmarshall

Original post by emily24

I can't view the ms file all I get is arsseys water Mark any help please??

Have you got the most recent update of Adobe Reader? If not, update and try again, it should work then :smile:

Reply 194

Phenylethylamine_

Ahh - I did the correct working out initially for Q3, got the differentiation correct but when working out x, I got up to -1/9pi and I was going to change it - but then at the end moment, I crossed my initial working out, put a cross in it and did some other working out. The work out with a cross in it was still readable. I know it's highly unlikely, but will I still get marks for this?

Also for 3tan2y differentiated in terms of x, I left it as

1/6+6(x/3)^2, I didn't simplify it fully in the end, will I lose a final accuracy mark?

Reply 195

emotionalwreck_

Thank you so much for uploading the solutions Arsey. I was feeling really unconfident when I came out of that exam, but now after looking at the solutions I feel better, so thank you :smile:

Reply 196

Umby

Original post by The_Pen

I solved that by using the R sin(3x+a) identity and got the same answer as Arsey. I hope I won't get penalised.

You could write it as that.

I did this. Got to be and alt method, it works perfectly using harmonic form. I even subbed the stuff back in the check they were correct. They can't penalise you for using an alternative method that is taught for the very same exam, surely D:.

Reply 197

masr123

Original post by tangkykiet

The last question 8d, do you get 1 mark if you wrote down the equation ? Answer pleasee thanksssssss

how would anyone know? some people.....

Reply 198

joneasy

Original post by raheem94

lol

Which question are talking about?

ok question 3 where you had to find the x coordinate of the turning point, did you have:

3cos3x + √3sin3x = 0
could be written
cos3x ( 3 + √3 tan3x) = 0
so could you not set the cos3x = 0 then get another answer??
i understand that theres only one x cordinate in the range where the turning point is but if your able to divide by cos 3x then surely you could take it out as a factor??

Reply 199

dsinghdahiya257

10

Q7b: For rewriting dy/dx in terms of x, instead of "arctan" I had put down "tan-1", would I lose marks?
Will I lose marks for not drawing in the asymptotes in Q7e?. If I don't lose any marks for these two parts then I think I've got 75/75.

Cheers for the MS Arsey :smile:

(edited 11 years ago)

C3 June 2012 - Post Exam Thread - Solutions and Paper in the FIRST POST

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