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OCR MEI FP1 May 18th 2012 PRE/POST DISCUSSION!

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    (Original post by johnstong)
    Does anyone know where the marks would come from for the inverse of the 3x3 matrix A? I'm a bit worried as it was 5 marks
    This is just a guess going from previous past papers / judgement, but:

    M1 mark for use of B
    M2 mark for 79 or 1/79 seen
    M3 mark for substituting in k=-3 (maybe, I can't remember 3 days later whether this was it / necessary for this part of the question)
    A2 for for correct inverse (minus one for each error?)
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    ahh nice one thanks. I just stated AB at the top (with the k substituted in) then put 1/79 B do you think that would get me full marks then?
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    (Original post by johnstong)
    ahh nice one thanks. I just stated AB at the top (with the k substituted in) then put 1/79 B do you think that would get me full marks then?
    If you got the right answer, then yes. It wasn't really a question where you had to show vast quantities of working.
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    negged for doing well in an exam tut tut
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    Does anyone have the unofficial mark scheme
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    (Original post by doreyFP)
    Does anyone have the unofficial mark scheme
    na but quote me on any questions and I will tell you the answers...
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    (Original post by bossman42)
    Yeah I got something like that too.

    But how did you find the det of a 3x3 matrix :|
    You didn't have to, you could work out the inverse another way, the det wasn't involved (it's on the FP2 spec).

    What you had to do is re-arrange them like this (I can't remember the question exactly so excuse me if 49 isn't the right multiplier, I might have it mixed up with a practise exam I did XD)

    AB = 49I
    A-1AB = A-149I
    B = 49A-1
    A-1 = B/49
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    does anyone have the past paper? or a mark scheme to help me out

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