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

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    (Original post by CD223)
    How's your prep going?


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    It's going alright, I'm nearing the end of doing all the core 3 papers for a second time but I just can't get the hang of differential equations! Like I can solve them easily but it's he informationy ones that get me haha! Got a week and gonna go hard core lol, how about you?
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    (Original post by Baloney26)
    It's going alright, I'm nearing the end of doing all the core 3 papers for a second time but I just can't get the hang of differential equations! Like I can solve them easily but it's he informationy ones that get me haha! Got a week and gonna go hard core lol, how about you?
    Haha yeah I know what you mean. Weirdly M2 has helped with differential equations!

    I'm gonna focus entirely on the exams I have between the 5th and 11th over the next week!


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    (Original post by CD223)
    Haha yeah I know what you mean. Weirdly M2 has helped with differential equations!

    I'm gonna focus entirely on the exams I have between the 5th and 11th over the next week!


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    Agree with the M2 thing
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    Can someone help of part 4bii, always kept getting it wrong.

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    When t = T the growing colony is 45000 more than the dying colony. So (at T): growing colony - dying colony = 45000

    => 500e^(T/8) - 500000e^(-T/8) - 45000 = 0

    => e^(T/8) - 1000e^(-T/8) - 90 = 0

    Think about how you can make this into a quadratic and then solve. Remeber that some solutions might not be valid (depending on what variable your quadratic is in). Hope this helps. Didn't want to give it all away!
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    Can someone help me with the very last question on Jan 13 MPC4.

    You have to determine when dN/dt is a maximum value.

    This is like determining when the gradient of a line is a maximum. How is that done? taking the second derivative would enable you to determine whether stationary points are a maximum or a minimum.. But this is when the gradient is zero, not a maximum. So why would the second derivative help?

    Any help?


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    (Original post by Jimmy20002012)
    Can someone help of part 4bii, always kept getting it wrong.

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    I literally done this question yesterday, I actually loved this question, I could show you my solution if you want?


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    (Original post by JF2013)
    I literally done this question yesterday, I actually loved this question, I could show you my solution if you want?


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    Yeah I quite liked it till the last part. Could solve the equation and everything, it's just forming it kinda getting know where with it. Would be much appreciated


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    (Original post by Jimmy20002012)
    Can someone help of part 4bii, always kept getting it wrong.

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    Thanks. Just to make sure I understand what you have initially done, is this right. Using the app again haha.

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    (Original post by Jimmy20002012)
    Thanks. Just to make sure I understand what you have initially done, is this right. Using the app again haha.

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    Yeah - you're setting P equal to Q, but only when P is greater by 45,000


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    (Original post by CD223)
    Just purely past papers! How about you?


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    just done my first paper.

    in june 2010, I struggled on 6aii, and 6bii?
    confused on how to use the information given

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    (Original post by the_googly)
    just done my first paper.

    in june 2010, I struggled on 6aii, and 6bii?
    confused on how to use the information given

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    Does this help?

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    (Original post by CD223)
    Does this help?

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    thanks a lot! have you come across any similar questions like this?

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    (Original post by the_googly)
    thanks a lot! have you come across any similar questions like this?

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    Yeah they come up fairly often. Not every paper but certainly every couple of years


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    (Original post by CD223)
    Yeah they come up fairly often. Not every paper but certainly every couple of years


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    ill be prepared for the next one then!

    couldn't get my head around 9bii also

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    (Original post by the_googly)
    ill be prepared for the next one then!

    couldn't get my head around 9bii also

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    Right, I don't know if I'm just being stupid here....
    But the two ways I do this question I get different solutions? Does anyone know what I'm doing wrong?
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    (Original post by mamacita)
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    Right, I don't know if I'm just being stupid here....
    But the two ways I do this question I get different solutions? Does anyone know what I'm doing wrong?
    Why is the first way you did it squared?


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    (Original post by Jimmy20002012)
    Why is the first way you did it squared?


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    I squared both sides so I could try and rearrange so I only have cos
 
 
 
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