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Edexcel A2 C4 Mathematics June 2016 - Official Thread

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how many marks was question 4?
How was it not 1024pi/5
Reply 4122
Original post by Azzer11
Which question was the implicit differentiation one?

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3 I believe
Only thing I seem to have got different to everyone is co-ordinates for the last question.

Stored it in my calculator as (-1, 33/5, 16/5) and (3, 17/5, 4/5) so either I stored it wrong or I made a stupid error lol
For the volume question, how was it 544pi? It had to be 576pi as u had to work out the whole cylinder and take it away by the integral surely!
Original post by HarshaPeed
I Got 633 mins.


i got 0.439 days or something but it said to give it to the nearest min not to convert to mins. e.g like 0.5435 km is 0.544 km to the nearest m
did you have to convert to mins? :frown:
Original post by Smithy1597
How was it not 1024pi/5


That's the volume of the portion you take away from the entire cylinder
Reply 4127
Original post by BenGeorge
I found this 10 times easier than C3. Its amazing how much a change in mindset affect your grade.

What was the change in thinking ?
So annoyed at myself for messing up the implicit differentiation. Do you think I'll get any marks with like error carried forward or not?
I got 3164 minutes for the decay one anyone else?

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I got cos(theta)= -1/5. How many marks will I lose for this and i got part E) correct?
Original post by Whizbox
Only thing I seem to have got different to everyone is co-ordinates for the last question.

Stored it in my calculator as (-1, 33/5, 16/5) and (3, 17/5, 4/5) so either I stored it wrong or I made a stupid error lol


I got that :colondollar:
Original post by Whizbox
Only thing I seem to have got different to everyone is co-ordinates for the last question.

Stored it in my calculator as (-1, 33/5, 16/5) and (3, 17/5, 4/5) so either I stored it wrong or I made a stupid error lol


i think this is what i got
Original post by riffy123
For the volume question, how was it 544pi? It had to be 576pi as u had to work out the whole cylinder and take it away by the integral surely!


it wasn't 576pi either. it was 544pi - (1024/5)pi = 1696/5 pi
Marks for each Question:
1A) 6
2A) 1 B)3 C) 5
3A) 5 B)4
4A) 4 B)3
5A) 4 B)2
6A) 6 B)5 C)5
7A) 2 B)1 C)4
8A) 1 B)2 C)2 D)3 E)2 F)5
I think please correct me if I'm wrong.
Original post by ryanroks1
Wasn't it 60e^-2.5t?


I got that.
Original post by cjlh
My full solutions:

1) 1/8 - 15/16 x + 75/16 x^2 - 625/32 x^3

2) 0.6595, 1.083, 8/3 ln(2) - 7/9

3) (-2-4xy)/(2x^2 + 4 + pisin(0.5pi)), (3pi+62)/(pi+22)

4) x=e^(ln(60)-2.5t)), 633 mins

5) (-5root(3)/16), (4,5root3)

6) 3ln(3y+2)-2ln(y)+c, lambda=8, 4pi/3 - root3

7) k=17/2, 1696pi/5

8) {3,5,0}, r = {1,5,2} + lambda{-5,4,3}, k=2, cos(theta)=4/5, area=12/5, possible positions {3, 33/5, 16/5} and {-1, 17/5, 4/5}


Fairly sure E is actually (3, 17/5, 4/5) or (-1, 33/5, 16/5) or otherwise it doesnt fit on the line L2.
E = (1,5,2)+k(-5,4,3) so
1-5k=3 --> k= -2/5
5 + 4 x -2/5 = 17/5
2 + 3 x -2/5 = 4/5

You can do the same for the other value of E to work out if its on the line
Original post by Vannzzoo
I GOT EXACTLY THE SAME IM SOO HAPPY, hope they're right tho


Got all the same, except i got 634 minutes, or 10 hours 34 minutes
The exam went really well for except for the last 5 marker, could someone please explain to me how you were meant to do it as i literally spent about 25minutes on it and knew i had done one similar in the past. I was using the fact P was the midpoint and magnitudes were 2root2. But was proberly going off on a tangent :wink:
Reply 4139
Original post by Smithy1597
How was it not 1024pi/5


thats volume for under graph, S would be volume of the rectangular part (becomes a cone) subtracted by the volume under the graph

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