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Edexcel A2 C4 Mathematics June 2015 - Official Thread

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I'm not sure you should have been having to integrate that in the first place in C4. Was there a previous part to the question?

whoops sorry think i got muddled. it was 3^2x. i must have gotten 9^x^2 from somewhere else. fml, i black out after such exams LOL.

Reply 2781

Ripper Phoenix

Original post by C++

Or simply let 3^(2x) = (3^(2)^x) = 9^(x);

This then gives (1/ln(9) * 9^(x)) + C

this is absolutely wrong!

Reply 2782

emu_neutrino

Original post by talkbiology

Rings a bell! for the volume of revolution I got 13pi / ln3, any confirmation? :smile:

i got that too! wasnt sure though because i intergrated by substitution

Reply 2783

rachelc142

for the last question part b, I did the right method but when I went to work out my cone for h I did 9- x co ord of Q instead of 2 lmaooo what an idiot :-( how many marks do people think I could still get ?

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Reply 2784

Paublo

My answers for this paper were:
1) 2+5x/4-25x^2/64
3rt2/2
181/128
2)(2x-3y)/(3x+8y)=dy/dx
+-(24/5,16/5)
3)x=4ln(2)
12+32ln(2)^2-32ln(2)
4) A=5,1,3
p=15
31.82
d=7.46
5)27/32
a=2 b=-5
6)k=4
4pi/3 + rt(3)/2
7) 1/(p-2) - 1/p
0.473
8) x=2 - 1/ln3
area = 13pi/ln3
this is most of the questions that i wrote down my answers to, I am confident in most of them although I am prone to the occasional stupid mistake so if you disagree then I will not argue with you.

Reply 2785

maj156

Original post by mahatma ghandi

its 473 years, it's in 100s of years bro

no it isn't

Reply 2786

PoloMaxima

Original post by JulianS96

I got the same thing too.
Something like 12000 -6 = 4000e^1/2sin2t
Then ln2.9985 = 1/2sin2t
Therefor 2ln2.9985 = sin2t
Therefore 2t equals Math Error

P was population measured in thousands, so 4000 people meant P became 4

Reply 2787

talkbiology

Original post by PaulCJH

My answers, judging by other people's opinions I think they're right:

Thank you so much! If these are right then the only one I got wrong was 7c), the DE populations one where I didn't realise it was in thousands -.-

Reply 2788

sahlean

Original post by Bustamove

with the 32ln(2)^2 -32ln(2) + 12, I simplified it even more to 64ln(2) - 32ln(2) +12... ended up getting 32ln(2) +12.... is that still correct or would I lose a mark?

(ln(2))^2 is not the same as ln(2^2) or 2ln(2)

Reply 2789

jf1994

Original post by sagar448

What do you guys think Grade boundaries will be for an A*?

69/70

Reply 2790

Paraphilos

Original post by abigail love

whoops sorry think i got muddled. it was 3^2x. i must have gotten 9^x^2 from somewhere else. fml, i black out after such exams LOL.

Ok. In that case, you make a substitution of

u(x) = 3^{2x}

in order to solve the integral.

Reply 2791

STATER

How many marks for integrating correctly, finding volume of cone correctly, but manipulation error in between, leading to the wrong answer?

Reply 2792

joe1545

**** THIS. Im off to ecaudor on Thursday, so I can drown my sorrows there

Reply 2793

Humbers

Original post by joanneeve

anyone get 53pi/ ln3 for the last question?

its 13pi/ln3 sorry :c

Reply 2794

Rubgangsci

Original post by rachelc142

None 😉

Probably 3 or 4

Reply 2795

Maths2002

If I put 27.1 instead of 0.473 in question 7, I will lose only one mark right? I did put 0.473 as radian is default but then wonder why it is so short and changed it to degree :frown: