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Mr M's OCR (not OCR MEI) FP1 answers June 2012

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    (Original post by ninuzu)
    Hi Mr M, thanks for these
    For 9.(ii) your answer is 1/2(1, root3, -root3, 1). I halved everything and left it as a decimal so I got (0.5, 0.866, -0.866, 0.5) Would I still get the marks??

    I'm trying to make the brackets look vaguely like a matrix there.
    Also, for the shear question, I put a shear parallel to the x-axis scale factor 2, would that gain any marks?
    Decimals in that matrix is fine.

    You might drop a mark there. I haven't looked at a FP1 mark scheme for a few years so I don't know how fussy they are about language.
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    (Original post by Mr M)
    Probably but not certainly.
    Sorry I double posted now can't edit so ignore my other quote
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    Thank you again for the answers, I got one half of the matrix right and one half wrong for 9) ii) ? How many marks would I lose?
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    (Original post by Ugachaka)
    Question 6 (ii) was (1/A - 1)(1/B - 1) where A and B are roots, i think? . I got the answer to this as 3, how did you get 8/5?
    c/a from quadratic?
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    (Original post by Mr M)
    Decimals in that matrix is fine.

    You might drop a mark there. I haven't looked at a FP1 mark scheme for a few years so I don't know how fussy they are about language.
    I also put this, they usually mention the term invariant but it means more or less the same thing :/
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    Mr M, could you post Question 6, what was the original quadrtatic?
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    (Original post by Mr M)
    c/a from quadratic?
    I think i might have overcomplicated the question, when you subsitute in the (1/u+1)? does this change the roots aswell?
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    yeah when you put 1/(u+1) the new roots are (1/x) -1 as that is the point of the substitution
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    for qs 6 , would you get a error carried forward for part ii?
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    (Original post by As_Dust_Dances_)
    3/2 - 1/(n+1) - 1/(n+2) or something like that is what I got for 8ii)
    This is correct and would get full marks.

    Mr M is far too quick; some of us still have to teach! (A day of FP2 for me)

    I can concur with all his (edited) answers. I would suspect that for Q4 n(n2+1) would get full marks, but can't guarantee it.
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    For the summation series question (first part) finding the sum to N, instead of simplifying the answer to 3/2 and the n stuff i put 1 + 1/2- 1/n+1 and the other n thing. Would i lose a mark?
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    (Original post by BenjaminKyle)
    how many marks in total would i lose for stupidly drawing the loci |z|=|z-8| due to a misread (so that I ended up with a vertical line through (4,0) .... although i did do the circle and shade the right area of the circle correctly) - however i am worried i've made myself lose a lot of marks here as there was more than one part to the question dependent on the loci (such as the intercepts). Ahh i feel so ridiculous, this kind of problem never normally phases me, i honestly don't know what happened!
    I'd imagine you would get carry on marks anyway, for drawing the wrong loci in the first place.
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    would you say this was a harder or easier than average paper? personally i thought the only tricky question was the induction Q which i could not do, but no one else seems to be fased by it.
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    for that induction question you have to do [SUM OF 4*3^k] + [4*3^(k+1)] since you have assume P(k) to be true you can then use it again
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    (Original post by crazymanny00)
    for that induction question you have to do [SUM OF 4*3^k] + [4*3^(k+1)] since you have assume P(k) to be true you can then use it again
    i did that but i couldn't get it into the right format. how many marks do you think i lost
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    Mr M,
    I may have been a little bit silly and misread 6ii and thought that they were asking for (1/α -1) and (1/β -1) to be worked out separately. I worked these out to be:
    -11/10 +- i root(39)/10

    How many marks out of three do you think I would get?
    Thanks
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    why was the rotation clockwise, because according to the formula book, its anticlockwise

    Click image for larger version. 

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    because when you do cos -1 (0.5) you get 60 degrees so it must be 60 degrees anticlockwise
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    (Original post by KoalaKim)
    why was the rotation clockwise, because according to the formula book, its anticlockwise

    Click image for larger version. 

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    because when you do cos -1 (0.5) you get 60 degrees so it must be 60 degrees anticlockwise
    You need to look at the sin part. -sin(60) = -0.866 when we wanted it to be positive in that position.

    So the angle we are rotating anticlockwise must be -60
    Hence 60 degrees clockwise
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    (Original post by TehCoolNerd)
    You need to look at the sin part. -sin(60) = -0.866 when we wanted it to be positive in that position.

    So the angle we are rotating anticlockwise must be -60
    Hence 60 degrees clockwise
    so why does the cos bit give you positive 60?

    oh, i get it!!! how many marks will i loose???
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    (Original post by KoalaKim)
    why was the rotation clockwise, because according to the formula book, its anticlockwise

    Click image for larger version. 

Name:	Untitled.png 
Views:	93 
Size:	14.2 KB 
ID:	153224

    because when you do cos -1 (0.5) you get 60 degrees so it must be 60 degrees anticlockwise
    I double checked by drawing a diagram of the unit square under the transformation and it turns 60 degrees clockwise. That was also the formula I used

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Updated: June 24, 2012
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