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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.
    How many marks would you get on 10iii) if you got two set of coordinates including the correct set and no further working?
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    (Original post by daisyrchds)
    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!
    Im guessing you probably got the wrong value of k like me. The correct value of k was -5
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    think i got about 60-63? do you reckon this would be an a?
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    (Original post by waheed786)
    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!
    1 probably.
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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,

    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 Mr M)
    6. (i) Centre (0, -4) and radius 2 \sqrt{10} (3 marks)
    Hi Mr. M, I got the radius as \sqrt{30} because I thought 16+24=30 (no idea why), but I got the center and the next part right. Drop one mark? two?
    Thanks!
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    (Original post by rubberduck5)
    think i got about 60-63? do you reckon this would be an a?
    I can't say for sure. You must be A or very close to an A.
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    (Original post by cleverslacker)
    Hi Mr. M, I got the radius as \sqrt{30} because I thought 16+24=30 (no idea why), but I got the center and the next part right. Drop one mark? two?
    Thanks!
    1 probably.
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    (Original post by Majeue)
    Im guessing you probably got the wrong value of k like me. The correct value of k was -5
    nope, i got -5!
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    (Original post by Ecomax)
    How many marks would you get on 10iii) if you got two set of coordinates including the correct set and no further working?
    There is another point of intersection but the line is not a tangent at that point. Drop 1 probably.
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    (Original post by hayhayhay1)
    why cant you type them up, as i cant remember half of them. sorry for the inconvenience
    Far too lazy/busy. Ask your teacher for a copy of the paper tomorrow?
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    Sorry to ask again just wondering if its drop a mark for \sqrt{40} rather than 2\sqrt{10} on the circles radius ?
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    For Q4 I put 39/12 but didn't cancel it. Will I sti get full marks? Thanks.
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    (Original post by queketth)
    Sorry to ask again just wondering if its drop a mark for \sqrt{40} rather than 2\sqrt{10} on the circles radius ?
    No, that's fine.
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    If we wrote the transformation out correctly, wrote the (x+5)^2, then expanded it? Lose any?
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    (Original post by olivers16)
    For Q4 I put 39/12 but didn't cancel it. Will I sti get full marks? Thanks.
    yes
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    How many marks do you reckon i'll get for question 2 for putting y=x^2 doing that to get something to the power of 4, then putting z=y^2 and then getting a quadratic to work out x from there? I know it was stupid and wouldnt actually end up calculating it for ^6, I had one of those blank moments... but i did use the substitution method...
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    (Original post by Mr M)
    No, that's fine.
    Thanks but so frustrating 71/72.... :eek:
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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.
    please you tell me How many marks would be lost for not discounting the (0,-9) co-ordinate in 10iii)
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    4)i) I got 3(x+3/2)^2+29/12 due to calculation error of 3(10/3 - 9/4) would that be -1 mark?

    4)ii) So obviously my vertex was (-3/2,29/12) would that also be -1 mark?

    10)iii) I didn't state the x=0 co-ordinate doesn't work in the tangent, instead I just scribbled the co-ordinate out and just used (-2,-27). Would that also be -1 mark?
 
 
 
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