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# AQA A2 Mathematics MPC4 Core 4 - 9th June 2015 [Discussion & unofficial markscheme] watch

1. (Original post by 2014_GCSE)
Can someone write out a step by step on June 2014, Q4)C)I) whilst it's been brought up.
Can't do it at all.
Sorry, I'm on my mobile having serious trouble uploading these pictures, but here it is (went full-out on the "step by step":

EDIT: they were upside down so posting again...
Attached Images

2. (Original post by datpr0)
Sorry, I'm on my mobile having serious trouble uploading these pictures, but here it is (went full-out on the "step by step":

EDIT: they were upside down so posting again...
You don't understand how helpful that is. Thank you!!!
3. JUNE 2014 4ci. FIRST HALF OF WORKING:

4. JUNE 2014 4ci. SECOND HALF OF WORKING:

5. (Original post by 2014_GCSE)
You don't understand how helpful that is. Thank you!!!
I am glad you think so ! It's taken a good 20 minutes extra ;/ because of having to upload so many times.
6. (Original post by datpr0)
JUNE 2014 4ci. SECOND HALF OF WORKING:

cant you do t+10 for the other one starting before aswell?
7. (Original post by datpr0)
I am glad you think so ! It's taken a good 20 minutes extra ;/ because of having to upload so many times.
Sorry to have taken your time up, but it's really helped me, so thanks for persevering with the upload.
8. (Original post by mrlemma)
cant you do t+10 for the other one starting before aswell?
In theory, yes; however, in reality no. Note that in the question it states "the value of the two paintings will be the same T years after 1991" - this is why you take T-10. If you take it as T+10, you end up with lnq^10 - ln2 = Tlnp/q but you don't know what q^10 is so you're screwed :P. If you use T-10 then you end up with a p^10 which you know from bi. = 5.
9. Anybody know what the highest mark an A* has ever been for Core 4?
10. (Original post by datpr0)
In theory, yes; however, in reality no. Note that in the question it states "the value of the two paintings will be the same T years after 1991" - this is why you take T-10. If you take it as T+10, you end up with lnq^10 - ln2 = Tlnp/q but you don't know what q^10 is so you're screwed :P. If you use T-10 then you end up with a p^10 which you know from bi. = 5.
oh when it says "the value of the two paintings will be the same T years after 1991"

it is basically telling you to put it starting at 1991... if you put t+10 then it may have been the same in that 10 year period you deleted!!

it would have asked... t years after 2001 then it would have been correct
11. How do you know when to dot a vector to a line or another vector?

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13. HIGHEST EVER MARK FOR AN A* (IN THE LAST 5 YEARS): 63
LOWEST EVER MARK FOR AN A* (IN THE LAST 5 YEARS): 58

Not too shabby folks.
14. (Original post by Starcrossed123)
I'll go through it now. Give me 5-10 mins
15. (Original post by 2014_GCSE)
HIGHEST EVER MARK FOR AN A* (IN THE LAST 5 YEARS): 63
LOWEST EVER MARK FOR AN A* (IN THE LAST 5 YEARS): 58

Not too shabby folks.
other than jan 11 where it was 68/75 for an A*. But yeah, typically they are delicious boundires
16. (Original post by Jimmy20002012)
How do you know when to dot a vector to a line or another vector?

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typically its when you are told to find the angle between two lines. Be sure to dot the direction vectors if you are dealing with two vector equation of lines.
17. (Original post by Starcrossed123)
You basically sub in values of X to make the brackets = 0 for 2 of the 3 letters so you can work out the remaining letter.

18. Really hoping for a single vectors question around the Q6 mark, with exponentials/differential equations as the final question. How about you guys?
19. (Original post by EHR223)
typically its when you are told to find the angle between two lines. Be sure to dot the direction vectors if you are dealing with two vector equation of lines.
Right! Could you explain that a bit more, I do seem to get the questions right but how to you know for certain to dot lets say AP . CD = 0, or with the line direction vector is there some kind of rule you have to notice?

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20. (Original post by Jimmy20002012)
Right! Could you explain that a bit more, I do seem to get the questions right but how to you know for certain to dot lets say AP . CD = 0, or with the line direction vector is there some kind of rule you have to notice?

Posted from TSR Mobile
The scalar product = 0 if they're perpendicular and as such if you're told that AP-> is perpendicular to CD-> you know you'll probably need to use the scalar product to find the answer they want.

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