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# Edexcel A2 C4 Mathematics June 2015 - Official Thread watch

1. (Original post by C++)
Oh dear lord;

This means that:

As stated.

ma bad i ****ed up, sorry for calling you out :c
2. (Original post by Mishy96)
I got 60 something for the angle
The angle was 31.8
3. for the last question i got the volumn of cone wrong and therefore the final answer wrong. but the integration part seems right. how many marks will i lose??
4. How many marks do you think I will lose for the last question? I integrated the curve correctly, getting 40pi/ln3. But when calculating the volume of the cone I accidentally used (2-1/ln3) and did not use (2-(2-1/ln3)) for the height, so when I subtracted the 2 volumes, I got (67pi-54(pi)ln3)/ln3.
5. pls arsey you're killin me now

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6. (Original post by mbcns)
Could someone check this is right please?
for the last question,
y= 3^x, dy/dx = 3^xln3
when x =2 dy/dx = 9ln3
so tangent=
y-9=9ln3(x-2)
y= 9ln3x-18ln3+9
so it cuts the x axis where
9ln3x-18ln3+9=0
9ln3x= 9-18ln3
ln3x= 1-2ln3
3x= e^1-2ln3
3x= e/ln9
x = e/3ln9
When u multiply out the bracket it becomes 9xln3 not 9ln3x so u then divide 18ln3 - 9 by 9ln3 to get 2-1/ln3
7. (Original post by Otchina)
I think that part was 6 or 7 but there were other bits you had to do to get to this point so I f you did the previous steps well, you'd probably get 4 marks
8. (Original post by joanneeve)
if the last question i didnt change 3^2x to 9^x but the method was right, how many marks would i lose?
You wouldn't lose anything, you can still work out the volume with 3^2x.
9. (Original post by Emmi12345)
I had a STEP exam right after as well
10. How many marks do u guys think would be for just finding the volume 40pi/ln3 in the last Q.
11. I was the only one with mad working out on the back page when the invigilators collected the papers in. Everyone else must have got the answer quickly or given up lol

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12. (Original post by kingaaran)
You've worked out where it crosses the y axis...

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umm i don't think so? it crosses the y axis when x=0 and the x axis where y=0
13. (Original post by aero-1997)
Do you guys think i can get an A* if I have 68-C3 67-C4.
definitely
14. how many marks will I lost out of 3 if I have used dot product, but get the wrong angle?
15. (Original post by joanneeve)
if the last question i didnt change 3^2x to 9^x but the method was right, how many marks would i lose?
None if you got the right answer. It wasn't imperative that you changed it to 9^x. I personally left it as 3^2x, ended up doing a substitution somewhere along the way and it all worked out fairly quickly and nicely.
16. How many marks would I get for the last and 3rd to last questions finding the correct integral but not the correct area?

17. Attachment 429845429847
Attachment 429845429847429800

Thanks to MC1996
Attached Images

18. (Original post by Humbers)
ma bad i ****ed up, sorry for calling you out :c
No problem.
19. (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.
bump for those who couldn't find it
20. randomely guessed k as 3.. l0l

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