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

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    coordinates for C were (-9, -2, 18) ?
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    can someone explain question 1b? i got like 1/3ln5-1/6ln25 and i had no idea where to go from here. how did everyone got their solution? and does any one remember how many marks was it?
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    Some people are getting some weird answers for solving that DE, anyone else get c=5?
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    (Original post by I Persia I)
    I did, can anyone else confirm?
    Me too. But apparently the answer was actually 11/8? That's what a couple of my friends got.


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    (Original post by kateyl)
    Is it just me or I thought that the other coordinate for E (not the (11,0,0)) one didn't have a zero anywhere????
    Sameee


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    For the differential question: dr/dt= k/pir^2. But since we want it with respect to r, dt/dr = pir^2 / k, right?? I got 1/3. Seems logical since the rate was lower... at 0.5, as opposed to 4.5
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    (Original post by science33)
    can someone explain question 1b? i got like 1/3ln5-1/6ln25 and i had no idea where to go from here. how did everyone got their solution? and does any one remember how many marks was it?
    Turn the 25 into 5^2 and then use log rules to times the 2 by -1/6
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    (Original post by WillowXxx)
    is it only me who didnt get 5. something for the other value of x on the Rcos(x+1.19) question? i got 3.34
    no im the same! because it said 0<x<pi/2 so I don't know where people got 5 from?
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    (Original post by Hamzz9)
    Me too. But apparently the answer was actually 11/8? That's what a couple of my friends got.


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    Ahh dunno then, probably wrong :/
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    (Original post by science33)
    can someone explain question 1b? i got like 1/3ln5-1/6ln25 and i had no idea where to go from here. how did everyone got their solution? and does any one remember how many marks was it?
    1/6ln25 = 1/6ln5^2 = 2x1/6ln5 =1/3ln5
    Should be 3ln5 Aswell
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    (Original post by I Persia I)
    Ahh dunno then, probably wrong :/
    Yeah think it was like (1+3/8)/(3/4 +1/4) = (11/8)/1 =11/8
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    (Original post by I Persia I)
    Ahh dunno then, probably wrong :/
    i got the same, just curious as to where abouts i went wrong lol
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    (Original post by science33)
    can someone explain question 1b? i got like 1/3ln5-1/6ln25 and i had no idea where to go from here. how did everyone got their solution? and does any one remember how many marks was it?
    Should have been 3ln5 - 1/6ln25 then ln25=2ln5 so 1/6ln25=2/6ln5 and 3ln5-2/6ln5= 8/3ln5
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    I weirdly enough got x=-3/4 and x=1/2 and I input the x value in inverse sin to get q? Out of 5 how many marks would that roughly get me
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    Can anyone remember the differential equation? Q8a


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    (Original post by amyrah)
    coordinates for c were (-9, -2, 18) ?
    i got that
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    Hell .

    Everyone's saying 5/256 for the binomials and I think I wrote 5/64, clearing having forgotten multiply by 1/4.
    I didn't prove that h(x) is a decreasing function correctly (mind gamed myself to rewrite that answer).
    I didn't finish the vectors question having skipped it after finishing a. to come back to later (almost finished b but not quite and no attempt on c) because I was checking my answers for the harder questions.

    So... that's probably -1 mark (hopefully e.c.f for the estimate), -2 marks (scribbled out h'(x), like a boss), -2 marks (almost completing b. which I'm really annoyed about because it was easy) and -4 marks (no attempt at part c - anyone know what the question was as I didn't even read it?).

    Which is -9 marks, putting me at 66. You guys think that will still be 90 ums? (I have probably ~96 ums in C3, accounting for any silly mistakes).
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    (Original post by George1231)
    please try and add answers as I found the paper really hard and probably got a lot wrong
    1) A=3 B=-1
    b) 8/3ln5
    2)a r=root 29 alpha=1.19
    b)max value root 29
    c)x=5.09x=0.568 or 5..72
    3) d=1
    b) (2x+1)(2x-1)(2x-3)c) h(x)=(1=2x)^-1 differentiate shows its decreasing
    4a) 1+x-2x^2
    b) 1/4 -x/16+5x^2/256
    c)0.2313
    5a)gradient of normal -1/2
    b) equation of normal y=2x-1/2
    c) x cooridinate -1/8
    6a) 60 degrees
    B) (15,3,2)
    C) got wrong (11,0,0)
    7a) 1/4-ln2
    b)11/8
    8a) x=9/20-1/2(t+1)-1/20(1+t)^2
    b)dr/dt=k/pir^2
    c) 3
    Somehow i recognise most of these answers, put x=1/3 for binomial expansion but dont think i got 0.2313 which means i made a sign error somewhere. For the sin values last question i only remember getting 3.33 and something else for my two solutions, so not sure about that quesion. YESS I GOT -1/8 FOR Q. For question 8a) differential equation, they didnt ask for a specific from did they? I've seen papers where they leave it in a form that isnt x=f(x)
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    (Original post by tiffanyyyyyyy)
    For the differential question: dr/dt= k/pir^2. But since we want it with respect to r, dt/dr = pir^2 / k, right?? I got 1/3. Seems logical since the rate was lower... at 0.5, as opposed to 4.5
    Nope, when something is inversely proportional it is always k/x. At you method of pir^2/k, the rate of change would increase as r increases - which is wrong
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    for 3C I put in multiple values of x above 2 to show that it is decreasing, would I get any marks?
 
 
 
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