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    (Original post by Mr M)
    No, that's fine.
    for the decreasing function one I found dy/dx = 4x -1 but didn't make dy/dx zero...

    then found the 2nd derivative after that and for some reason put X < 4 how many marks would I lose for this?
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    For 5ii) I put ( (2/x) + 5)^2
    Is that completely wrong?
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    have you got the questions?
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    For 8, I got one of the midpoints wrong but the other one right. I then got the gradient of both the line and the perpendicular correct. However when i therefore substituted in my values, I got 3x + y - 2 = 0 . How many marks would I get? Thanks
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    Did anybody else get 10(ii) as a maximum? or was it just me
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    For question 9 i worked out all the points that it intersects but i only wrote next to where it crosses an axis like -3/2, -6 and 2. Would i get the marks?

    PS - Thanks for the answers!
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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&lt;-\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 &lt; \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 question 9iii, not too sure what I did but I ended up with co-ordinates (1/4 , 4) any idea how many marks I'll lose?


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    Hi Mr M,

    For Q 9)iii I believe I got the x-coordinates correct but for some silly reason got the incorrect y-coordinates and hence got the Distance incorrect. How many marks should I expect to lose?

    Also, for 10)iii I got the x-coordinate of -2 correct but inserted it into the wrong equation and got -43 for the y-coordinate. How many marks should i expect to lose?

    Thanks for the effort
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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&lt;-\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 &lt; \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, what was question 7ii and how did you go about it? If I can remember correctly I found the min point using dy/dx and then just said x<min point (cannot remember co-ordinate).

    I appreciate you putting up these answers


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    Mr. M, if I did all the correct workings for 10i but got k = 4, then did all the correct workings for 10iii but then got the wrong coordinates, how many marks would I lose? Would I get all the marks for ECF, or if not, how many would I lose?
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    Or does anyone else know what question 7ii was and how it was done?


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    Can someone please explain this to me (ii) (5 marks) , I think I got that and then changed it to x>0 or x<5 , how many marks will I lose?
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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
    I got k=-5 but got the same co-ordinates
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    could you maybe take a photo of the paper and post it?
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    what was 6ii and 9iii I forgot the questions
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    Damn it, lost a lot of marks here. So disappointed with myself especially with everyone on here saying it was an easy paper Time to pick myself up for C2!
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    Does anyone have the actual paper/questions?
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    (Original post by Wowzerss)
    Or does anyone else know what question 7ii was and how it was done?


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    (2x-4)(x-3) </= 12
    2x^2 - 4x - 6x +12 </= 12
    2x^2 - 10x </= 0
    x^2 - 5x </= 0
    x(x-5) </= 0
    x = 0 or x=5

    draw inequality curve. as it is less than zero its the part of the curve below the x axis.
    so 0</= x </= 5
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    (Original post by roar96)
    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...
    Sorry but I don't think that will gain any credit.
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    (Original post by Goods)
    please you tell me How many marks would be lost for not discounting the (0,-9) co-ordinate in 10iii)
    Just 1 I expect.
 
 
 
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