Mr M's OCR (not OCR MEI) Core 2 Answers May 2016

For the last question, i used the CAST diagram with 60 degrees and i got the same answers but in degrees rather than radians. How many marks will i lose?
Also, for 5bi, i got the answer but i ended up writing 4a^2 + 6a -2, would i lose any marks for doing that?

Hi

For question 3ii) How do you know what the constant was? I used 3, but i know now that it's wrong, can you show the method please.

If i left 9iii) as

x = (1/3π)/a

And

x = (4/3π)/a

would i still get full marks?

Thanks

Mr M's OCR (not OCR MEI) Core 2 Answers May 2016

8.
(ii) Stretch parallel to the y axis scale factor $\displaystyle \frac{1}{9}$ (2 marks)

How many marks would I lose for putting stretch parallel to the x axis scale factor 1/9?

For 8ii) I wrote stretch parallel to the x-axis by scale factor x/(x-2) will this get any marks because it produces the same graph or does it have to be in terms of numbers only and no variables?

Hi Sir,
If I used my answer for a from part ii in part iii but did the question with the correct method, how many marks would I get?
Thanks

Question number? You need to give me a bit more to go on.

Mr M's OCR (not OCR MEI) Core 2 Answers May 2016


1. (i) 10 cm (2 marks)

(ii) 5.04 cm (2 marks)


2. (i) $\displaystyle \frac{3 \pi}{10}$ (2 marks)

(ii) $r=20.4$ (3 marks)


3. (i) $\displaystyle 27 +27kx+9k^2x^2 +k^3x^3$ (4 marks)

(ii) $k=\pm \sqrt{3}$ (2 marks)


4. (i) $\displaystyle \log_3 \frac{x^2}{x+4}$ (2 marks)

(ii) $x = 12$ (4 marks)


5. (a) $\displaystyle \frac{x^4}{2} -x^3 +2x^2-6x+k$ (3 marks)

(b) (i) $\displaystyle \frac{2}{a^2} - \frac{6}{a} + 4$ (4 marks)

(ii) 4 (1 mark)


6. (i) $k=91$ (3 marks)

(ii) $\displaystyle S_{16} = 978$ (2 marks)

(iii) $N=38$ (6 marks)


7. (i) Quotient $x^2-4x+3$ and remainder 0 (3 marks)

(ii) $x=1$ or $x=-1$ or $x=3$ (3 marks)

(iii) Show (2 marks)

(iv) $\displaystyle \frac{512}{15}$ (4 marks)


8. (i) Translation by 2 units in the positive x direction (2 marks)

(ii) Stretch parallel to the y axis scale factor $\displaystyle \frac{1}{9}$ (2 marks)

(iii) Sketch showing $(0, \frac{1}{9})$ as the only point of intersection (2 marks)

(iv) $x=6.73$ (3 marks)

(v) 9.60 (3 marks)


9. (i) $\displaystyle \frac{2 \pi}{a}$ (1 mark)

(ii) $\displaystyle a=\frac{5}{3}$ and $\displaystyle k=\frac{\sqrt{3}}{2}$ (3 marks)

(iii) $\displaystyle x=\frac{\pi}{3a}$ and $\displaystyle x=\frac{4 \pi}{3a}$ (4 marks)


Sorry guys I made a mess of 9(ii) at the start - I didn't notice k had to be positive. It's right now.

Oh yeah sorry, it was for Q9, part iii
I used a as 5/3 for part iii when it said it was a different value

You might still get 2 marks in the final part.

For 9iii when dividing by cosax does cosax=0 not become a solution

No.

It isn't a correct answer. There is a scale factor of 1/9 in 8ii.

Can you tell me why please