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# Edexcel A2 C4 Mathematics June 2015 - Official Thread watch

1. Guys for integration in C4 how are we supposed to tell which integration method we should use?
2. (Original post by Bustamove)
I made some massive stupid mistakes which made me head bang the table once I realised what I did....
e.g.
Question 9.. I forgot that K was a negative constant.. so wrote decreasing.. even though it was highlighted in BOLD.... like wtf.. how can I not see it? 2 marks gone...

question 2... I forgot the label the point where the graph intersects the x axis...
I worked it out, but I forgot to put it on... I also forgot to put the asymptote for the second graph.. (I just wrote y=5 at the bottom but I didn't label it.. Worked it out, forgot to draw it in the diagram..)
Thats 3 of the easiest marks lost from that 6 marker diagram question...

this continues throughout my paper.. I don't know what the **** was wrong with me in that exam hall....
nah you'll be fine, docking 2/3 marks here and there will probably still land you a good solid A
i couldnt even figure question 9 out, im pretty sure if id done that in timed conditions at home with a bowl of icecream id have got a lot more marks hahah, exam halls freak me out
3. (Original post by joe1545)
So say if the exact area under the curve is 10, and the approximated value is 9,

then the percentage error = (10-9)/10 * 100 = 10%
ye.
4. (Original post by Bustamove)
UCL for economics
A* emphasis on maths... I've definitely not met that criteria..
I can only hope that I get AAA and a very high UMS in maths.. maybe they'll still take me...
haha i'm the same. was going to go to ucl for economics but doubt it after c3
5. Does anyone know where I can find the PiXL papers which predict what will come up tomorrow at all? Cant get them from the website as they you need a membership -_-
6. ill have a go at that when im done with my paper, watch this space!
7. (Original post by tazza ma razza)
I got UCL economics as well as my firm!

You sitting S4 as well by any chance? I got that first then c4 :/ gonna probs die after tomorrow
wahh s4 this is why i was questioning whether i should go to ucl for economics
too many geniuses
8. Split the variables and you should get :

1/(5000-N)dn = (Kt-1)/t dt

Simplify the right hand side to Kt/t -1/t = (K- 1/t) dt

Integrate both sides should be pretty easy.
Given that in question B they say you need to find A, meaning in question a instead of writing +c, write +A,

then rearrange to get there format.

9. Just did the paper... Sorry if Part b isn't very clear

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10. (Original post by ember8)
feel for you, how did you find c3? hope they lower the grade boundries by atleast 4 ums *fingers crossed*
Fairly tough but *if* the grade boundaries are lowered by 4, I'd be happy cos then I could get 80ums, which is what I need
11. Guys, what are the formulas of the shapes we are expected to know for questions such as connected rates of change?
12. (Original post by ember8)
Between 13 and 14, so I'd go with Arsey's.
56-58 for the A
63-65 for the A*,
70-72 for the 100 (I hope )
13. Could someone help me with this question please. Thank you.

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14. (Original post by anonwinner)
wtf is that
http://www.examsolutions.net/maths-r.../example-3.php
15. (Original post by Bustamove)
I think I got an A for econ3.... I went from not being able to finish a paper 2 days before the exam to doing every question in the paper... I did question 10... I kinda struggled with thinking about points for contestability but I manage to get at least 3 down with 2 application references, so I think I should get at least around 12/16 for that question... maybe a little lower... but overall I think I did pretty decent...

For C3 though, I'm really gutted over it... I spent less time on C3 as I was pretty good at it at the time and I couldn't do Econ3, so I panicked and spent 2 days straight on econ 3 before the exam... by the time I got the C3, I was a little out of touch with it and made so many stupid mistakes..

I may have gotten a borderline A or maybe a high B.... that's not good enough.. I need a A* for maths...

All we can do now is do our best in C4 and S2/M2 (which ever one you're doing)...
even if we don't get an A*, we can try and get the highest possible ums above 480.. hopefully, having a high enough ums above 480 will give be enough for the uni to give us some leeway...
Ah dude, you're in the same position as me.
I was struggling with it too but in the end I think I got an A in econ3 too, I probably would've lost marks for 10b because I spoke about ebikes rather than just bicycle manufacturers ffs
16. (Original post by maccisha)
there is a diffferentials section on this pdf that might help?
Thankyou!
17. (Original post by ember8)
nah you'll be fine, docking 2/3 marks here and there will probably still land you a good solid A
i couldnt even figure question 9 out, im pretty sure if id done that in timed conditions at home with a bowl of icecream id have got a lot more marks hahah, exam halls freak me out
nah.. it builds up.. I only gave 2 examples.. I haven't told you about my failure on the 6 marker for question 5 (the one for finding the coordinates, only managed to get to the differentials) and my trig identities... I couldn't solve it because I used Tan2A = 2Tan/1-Tan^2A.... don't know why I did that.. I can't believe I didn't used Tan2A = Sin2A / Cos2A..
and when finding the solutions, I used the CAST diagram, but then I don't know why my brain didn't compute, but I didn't draw it facing negative.. I thought it was positive even though the angle I got was negative... (if that makes sense)

anyway, what's done is done.. my best case scenario is actual 56-57 based on Arsey's markscheme... I could have saved my self and secured my self a definite A even with an extra 1 or 2 marks if I had not shot myself in the foot.... every mark counts...
18. (Original post by Leking9)
Ah dude, you're in the same position as me.
I was struggling with it too but in the end I think I got an A in econ3 too, I probably would've lost marks for 10b because I spoke about ebikes rather than just bicycle manufacturers ffs
no, you wouldn't have... We shouldn't be discussing this here LOL, theres a econ thread.. but I'll try and keep it short...

The question didn't specifiy traditional bike manufacturers.. only stated bike manufacturers which was open to interpretation.. whether you wrote about ebike manufacturers or traditional manufacturers was fine... there was a massive uproar on this on edexcel econ 3 thread. Besides, in the extracts, some traditional manufacturers were also ebike manufacturers anyway, which will just lead to a massive mess even if it were specified...
19. HOW DOES LN(2X) Become 1/x when differentiated?
20. The thing with the vector's questions are I can do parts 5 out of 6 completely fine but the last part I have no idea what to do, especially when they throw in other letters to use. Although it may only be worth a couple of marks and it's my only weak part of C4.

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