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Edexcel A2 C4 Mathematics June 2015 - Official Thread Watch

1. (Original post by emu_neutrino)
yeah i did that as i havent really done intergation of a^x that much and didnt want to risk screwing it up so I put 3^x equal to u and i got 13pi/ln3 which seems to be what a lot of other people got.
damn! I should have done that.... That would have simplified everything LOL
Hopefully I can get some method marks for doing volume under curve minus volume of cone...
2. (Original post by 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.
These are the same as all of my answers. Is this a good sign??
3. So annoyed at myself, couldn't integrate 3^(2x)

So I thought it was 3^(2x)/ln3 for some reason

If only I'd realised 3^(2x)=9^x then I wouldn't have had a problem Hopefully that's the only marks I've dropped and I should still get method marks

Overall I thought it was a very nice paper for C4
4. (Original post by rory58824)
That's what people were saying, I got 2 lol.
(Original post by hxllyb)
i got k was 2.... ?!?!?!!?!
I got 4, but I am not too sure though...
5. (Original post by physicsmaths)
Lol i just did it in my head
Thinks he's hard.
6. (Original post by Mishy96)
How do you intergrate 3^2x for the last question?!
(3^2x)/(2ln3)
7. (Original post by milogillot)
no k=2 since you had to square root 4cos^2
K=4 because you times 2 again. Because dx= 2 cos du
8. Will I lose marks for not putting brackets for natural logs?
9. (Original post by HMusa)
Cheers. Do you remember what the integral was?
xe^(x/2)
10. (Original post by sat_freak)
Ability to count to 400 isn't a prerequisite for sitting in C4 though.

know, exams can stress you out in funny ways, ways you never thought were even possible.
It's not?! I thought question 1 was write out every number from 0 to 500... That's one I've got wrong already.
I know... I can't stop shaking constantly in an exam. It's terrible - my writing looks all spidery.
11. (Original post by Mishy96)
How do you intergrate 3^2x for the last question?!
The way I do it is really easy:

3^2x = (e^ln3)^2x = e^(2ln3)x

then integrate that to get : e^(2ln3)x/ 2ln3 = 3^2x/2ln3
12. how many marks do u have to lose to get an ungradeable
13. Arsey MS out>??>??>
14. Let me just say 3^x squared is 9^2x. 100% that's correct
15. (Original post by PoloMaxima)
P was population measured in thousands, so 4000 people meant P became 4
I did not see that in the question lol. Rip answer
16. where is arsey my son
17. damn... for finding the angle.. I used tan instead of sin...I don't know why but i just did.... how many marks do you reckon i'll lose? I got like 6.98 (3.sf)...
stupid mistake... everything else was correct tho... I reckon I should at least get 2 marks out of 3?
18. (Original post by Kinivo)
Yea buddy
Same 🎉

Posted from TSR Mobile
19. (Original post by Emmi12345)
It's not?! I thought question 1 was write out every number from 0 to 500... That's one I've got wrong already.
I know... I can't stop shaking constantly in an exam. It's terrible - my writing looks all spidery.
Lol @ spidery.......
20. (Original post by Paraphilos)
There is a general rule for the differentiation and integration of ; they involve multiplying and dividing by respectively. So you're probably correct.
If you're really stuck, you can write a^x as e^ln(a^x) which simplifies to e^(xln(a)) then do what you'd normally do when differentiating/integrating the exponential function.

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