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Mr M's OCR (not OCR MEI) Core 1 Answers May 2013 watch

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    What do you think my marks will be, if I got the wrong value for k. But my method for that and the rest of question 10 were correct but obviously my answers would have been wrong. ( I Got the wrong value for k as I STUPIDLY multiplied -3 and 9 to get....-18. Giving k=4) ECF?
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    (Original post by Mr M)
    Mr M's OCR (not OCR MEI) Core 1 Answers May 2013


    1. (i) 12 \sqrt 5 (2 marks)

    (ii) 4 \sqrt 5 (1 mark)

    (iii) 5 \sqrt 5 (1 mark)


    2. x=\frac{1}{2} or x=-1 (5 marks)


    3. (i) f'(x)=2-\frac{12}{x^3} (3 marks)

    (ii) f''(x)=\frac{36}{x^4} (2 marks)


    4. (i) 3(x+\frac{3}{2})^2+\frac{13}{4} (3 marks)

    (ii) (-\frac{3}{2}, \frac{13}{4}) (3 marks)

    (iii) -39 (2 marks)


    5. (i) Correct sketch (2 marks)

    (ii) y=\frac{2}{(x+5)^2} (2 marks)

    (iii) Stretch scale factor \frac{1}{2} parallel to y axis (2 marks)


    6. (i) Centre (0, -4) and radius 2 \sqrt{10} (3 marks)

    (ii) (-2, -10) (2 marks)


    7. (i) x<-\frac{1}{8} (2 marks)

    (ii) 0 \leq x \leq 5 (5 marks)


    8. 6x+2y-1=0 (7 marks)


    9. (i) Correct sketch with intersections at (-1.5, 0) and (2, 0) and (0, -6) (5 marks)

    (ii) x \leq \frac{1}{4} OR x < \frac{1}{4} (either will be marked correct) (3 marks)

    (iii) 4.5 (4 marks)


    10. (i) k=-5 (7 marks)

    (ii) Minimum (2 marks)

    (iii) (-2, -27) (5 marks)


    I'll be around to answer questions shortly.
    do you have the questions to the paper
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    (Original post by StephHowarth)
    For question 2, i put 8^-1/3
    Will I still get the mark? I don't know why I wrote it so weirdly, but it is technically still right isn't it?
    It is technically still right. I think that is probably ok.
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    Out of curiosity, for the transformations questions, would I still get 2 marks if i said:

    "stretch scale factor 1/2 in the y direction"? As opposed to parallel to the y axis?
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    (Original post by Mr M)
    No that's fine.
    thank you!!
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    (Original post by BankOfPigs)
    Out of curiosity, for the transformations questions, would I still get 2 marks if i said:

    "stretch scale factor 1/2 in the y direction"? As opposed to parallel to the y axis?
    Yes.
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    Mr M,

    1) If we expanded the brackets after transforming the graph -5 units in the x-axis (Question 5, ii.) would we lose any marks, bearing in mind I did write the bracketed form out before expanding it? and the expansion was correct, (x+5)^2=x^2+10x+25

    2) Could anyone give me the questions for 8 or 9?
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    (Original post by Mr M)
    Lose 1 mark in part (i) and 1 or 2 in part (iii).
    Thankyou, i was worried i was going to lose about 6
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    (Original post by hayhayhay1)
    do you have the questions to the paper
    Yes but I'm not typing them all in!

    I can't scan them as that is a breach of OCR copyright.
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    (Original post by Mr M)
    No that's fine.
    for the complete the square question I left it as 39/12 instead of 13/4 please say you don't lose a mark for not simplifying?
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    (Original post by Mr M)
    It is technically still right. I think that is probably ok.
    Great thank you
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    Question 6i 2(10)^0.5 vs (40)^0.5 lose a mark for non simplified surd form for the circles radius?
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    (Original post by Cowcat)
    What do you think my marks will be, if I got the wrong value for k. But my method for that and the rest of question 10 were correct but obviously my answers would have been wrong. ( I Got the wrong value for k as I STUPIDLY multiplied -3 and 9 to get....-18. Giving k=4) ECF?
    Well you will lose one in the first part and 1 or 2 marks later on.
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    (Original post by Mr M)
    Mr M's OCR (not OCR MEI) Core 1 Answers May 2013


    1. (i) 12 \sqrt 5 (2 marks)

    (ii) 4 \sqrt 5 (1 mark)

    (iii) 5 \sqrt 5 (1 mark)


    2. x=\frac{1}{2} or x=-1 (5 marks)


    3. (i) f'(x)=2-\frac{12}{x^3} (3 marks)

    (ii) f''(x)=\frac{36}{x^4} (2 marks)


    4. (i) 3(x+\frac{3}{2})^2+\frac{13}{4} (3 marks)

    (ii) (-\frac{3}{2}, \frac{13}{4}) (3 marks)

    (iii) -39 (2 marks)


    5. (i) Correct sketch (2 marks)

    (ii) y=\frac{2}{(x+5)^2} (2 marks)

    (iii) Stretch scale factor \frac{1}{2} parallel to y axis (2 marks)


    6. (i) Centre (0, -4) and radius 2 \sqrt{10} (3 marks)

    (ii) (-2, -10) (2 marks)


    7. (i) x<-\frac{1}{8} (2 marks)

    (ii) 0 \leq x \leq 5 (5 marks)


    8. 6x+2y-1=0 (7 marks)


    9. (i) Correct sketch with intersections at (-1.5, 0) and (2, 0) and (0, -6) (5 marks)

    (ii) x \leq \frac{1}{4} OR x < \frac{1}{4} (either will be marked correct) (3 marks)

    (iii) 4.5 (4 marks)


    10. (i) k=-5 (7 marks)

    (ii) Minimum (2 marks)

    (iii) (-2, -27) (5 marks)


    I'll be around to answer questions shortly.
    Mr M, I expanded, differentiated, subbed in -3 and ended up with K=-9 for some reason, must have been a slight arithmetic mistake, how many marks would I lose?


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    im guessing i got around 63 which is what i got in january hopefully ums will be higher than jan though
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    any suggestions on why for the last part of question 10 i got (1,0)?! I differentiated the equation given then equated it to 9 assuming they would have the same gradient, as y=9x-9 was the tangent to the curve. lots of questions, sorry!
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    For 5ii) I wrote (2/x+5)^2
    Have I lost all the marks?
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    (Original post by Mr M)
    Yes but I'm not typing them all in!

    I can't scan them as that is a breach of OCR copyright.
    why cant you type them up, as i cant remember half of them. sorry for the inconvenience
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    Mr M,

    For the last question I got two coordinates for A instead of 1 , I got (0,-9) and (-2,-27)(the right answer) how many marks do you think I lost?
    Thanks!
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    (Original post by ZachM)
    Mr M, I expanded, differentiated, subbed in -3 and ended up with K=-9 for some reason, must have been a slight arithmetic mistake, how many marks would I lose?


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    1 for accuracy and maybe more if any other part of your working was wrong.
 
 
 
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