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# OCR C2 exam Wed 25th May Watch

1. Is anyone going to make an unofficial mark scheme?
2. (Original post by student199919)
depending on what it's out of, maybe like 1/2 marks? what was the actual answer for the stretch one of 3^x-2?
I put stretch parallel to y axis by factor 1/9 , since multiplying by 1/3^2 gives 3^(x-2)
3. I am gonna start an unofficial mark scheme - I think this is about correct!

1i) 10cm (2m)

1ii) 5.04cm (2m)

2i) 3/10π (2m)

2ii) 20.4cm (3m)

3i) 27+27kx+9k^2x^2+k^3x^3 (4m)

3ii) +/-√3 (2m)

4i) log base 3 x^2/x+4 (2m)

4ii) x=12 (4m)

5a) x^4/2-x^3+2x^2-6x (3m)

5bi) -6/a+2/a^2+4 (4m)

5bii) 4 (1m)

6i) k=91 (3m)

6ii) Sum of terms = 978 (2m)

6iii) N=38 (6m)

7i) R=0, quotient = x^2-4x+3 (3m)

7ii) (x+1), (x-1), (x-3) (3m)

7iii) Prove (2m)

7iv) 512/15 (4m)

8i) Translation 2 units in positive x direction (2m)

8ii) Stretch scale factor 1/9 in y direction (2m)

8iii) Sketch, crosses y at (0,1/9) (2m)

8iv) x=6.73 (3m)

8v) Area =9.60 (3m)

9i) 2π/a (1m)

9ii) a=5/3 and k=√3/2 (3m)

9iii) π/3a and ? (4m)
4. (Original post by _Orion_)
What did people get for N with the arithmetic and geometric series?

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Honestly did that so many times and persistently got that N > 0
5. (Original post by student199919)
i think i got something like 38, i'm probably wrong
I got 38 as well, i spoke to a few people and they got the same
6. (Original post by AlfieH)
I am gonna start an unofficial mark scheme - I think this is about correct!

1i) 10cm

1ii) 5.04cm

2i) 3/10π

2ii) 20.4cm

3i) 27+27kx+9k^2x^2+k^3x^3

3ii) +/-√3

4i) log base 3 x^2/x+4

4ii) x=12

5a) x^4/2-x^3+2x^2-6x

5bi) -6/a+2/a^2+4

5bii) 4

6i) k=91

6ii) Sum of terms = 978

6iii) N=38

7i) R=0, quotient = x^2-4x+3

7ii) (x+1), (x-1), (x-3)

7iii) Prove

7iv) 512/15

8i) Translation 2 units in positive x direction

8ii) Stretch scale factor 1/9 in y direction

8iii) Sketch, crosses y at (0,1/9)

8iv) x=6.73

8v) Area =9.60

9ii) a=5/3 and k=√3/2

q9i 2pi/a
9iii i think is pi/3a and 4pi/3a
7. 3ii is wrong shouldn't it be k=0 and k=1/9
8. for 5bi) -6/a+2/a^2+4
if i left it as -6a^-1 + 2a^-2 + 4 will any marks be deducted?

and if i forgot to square and cube k in q3, do i lose a few marks or all?
9. (Original post by goharis123)
3ii is wrong shouldn't it be k=0 and k=1/9
They wanted coefficient of x^2 to equal the constant. The constant was 27 in this case so 9k^2=27 therefore k= +/- root 3.

I think? Many others seemed to get this and it was only 2 marks. I may be wrong.
10. (Original post by czj1997)
for 5bi) -6/a+2/a^2+4
if i left it as -6a^-1 + 2a^-2 + 4 will any marks be deducted?

and if i forgot to square and cube k in q3, do i lose a few marks or all?
Nothing lost on 5bi.

It was only 2 marks so probably dropped 2.
11. (Original post by sandpitturtle)
q9i 2pi
9iii i think is pi/3a and 4pi/3a
What about the stretch in a? I think maybe it is 2pi/a?

I got pi/3a as one solution but for some reason 2pi/3a for the other haha.
12. I got that k was + or - 1/3
13. (Original post by AlfieH)
What about the stretch in a? I think maybe it is 2pi/a?

I got pi/3a as one solution but for some reason 2pi/3a for the other haha.
yeah thats right! sorry must've missed typing that but luckily i remember writing it for the exam
and not sure about the last one really everyone got different things haha
14. (Original post by AlfieH)
They wanted coefficient of x^2 to equal the constant. The constant was 27 in this case so 9k^2=27 therefore k= +/- root 3.

I think? Many others seemed to get this and it was only 2 marks. I may be wrong.
I think K was the constant and so 9k^2=k so
9k^2-k =0 so k(9k-1)
And so k=0 and k=1/9 I may be wrong I dont know
15. 9ii) is 7π/a
See working out in the attached photo

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16. (Original post by AlfieH)
What about the stretch in a? I think maybe it is 2pi/a?

I got pi/3a as one solution but for some reason 2pi/3a for the other haha.
yeah 2pi/3a should be right, its amazing how quickly answers are forgotten after exams i have no idea if i put 2 or 4 on the top now
17. (Original post by sandpitturtle)
yeah thats right! sorry must've missed typing that but luckily i remember writing it for the exam
and not sure about the last one really everyone got different things haha
My logic was first solution is π/3a therefor π-π/3a = 2π/3a...

Probably wrong - only a mark at least.
18. Shall we put the mark scheme in Google Docs?

19. Overall, i think the paper was fine, maybe apart from 9ii, which I did not manage to solve, but lost some stupid marks here and there. Think the grade boundaries will be around the same as usual, e.g. 58-59 for A
20. Does anyone know how many marks each question was to add to mark scheme?

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Updated: May 25, 2016
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