Mr M's OCR (not OCR MEI) Core 2 Answers May 2013

Hi,
For the question with the tangent, i worked out the gradient of the tangent to be 4, instead of 3. I then proceeded correctly, found the equation of the tangent ect.. How many method marks do you think I will get? Thanks.

For the very last question, iii) i didn't have time to finish so i only wrote down 2 of the possible 3 values. Will i only lose one mark?

1) drop 1 mark

6i) drop 1 or 2 marks

8c) drop 1 mark

9i) This is fine

No problem with + c

drop 2 marks for trapezium rule

Mr M's OCR (not OCR MEI) Core 2 Answers May 2013


1. 6.39 (4 marks)


2. (i) 254 and 106 degrees (3 marks)

(ii) 71.6 and 252 degrees (3 marks)


3. (i) $64+960x+6000x^2$ (4 marks)

(ii) c = - 11 (3 marks)


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

(b) (i) $-12 x^{-2} + k$ (2 marks)

(ii) a = 2 (3 marks)


5. (i) 62.2 (4 marks)

(ii) 34.0 (4 marks)


6. (i) 963 (3 marks)

(ii) 17 (6 marks)


7. (i) Show ... (4 marks)

(ii) $\frac{37}{30}$ (5 marks)


8. (i) (a) (0, 1) (1 mark)

b) (0, 4) (1 mark)

c) Any value where a > 1 and any value where 0 < b < 1 (2 marks)

(ii) Show ... (5 marks)


9. (i) 15 (2 marks)

(ii) Show f(-0.5)=0 and $f(x)=(2x+1)(2x-3)(x+1)$ (6 marks)

(iii) $\theta = \frac{2\pi}{3}$ and $\theta =\frac{4\pi}{3}$ and $\theta=\pi$ (4 marks)


I'll be around a bit this afternoon and then part of this evening to answer questions. Please post in this thread rather than sending me private messages.

Hey Mr. M, thanks for the answers.
In question 4 I wrote +c instead of +k for the constant, does that mean I'll drop marks?
In question 8c) I said a=1, b=1/16 would a=1 be correct? You wrote a>1.
Finally (sorry for all the questions!) in question 9ii I divided f(x) by (2x+1) rather than showing f(-1/2)=0 and for some reason went on to get f(x)=(2x+1)^2(x+1), how many marks do you think I'd lose?

Thank you very much,
Amy

Mr M's OCR (not OCR MEI) Core 2 Answers May 2013
7. (i) Show ... (4 marks)

(ii) $\frac{37}{30}$ (5 marks)



9. (i) 15 (2 marks)

(ii) Show f(-0.5)=0 and $f(x)=(2x+1)(2x-3)(x+1)$ (6 marks)

(iii) $\theta = \frac{2\pi}{3}$ and $\theta =\frac{4\pi}{3}$ and $\theta=\pi$ (4 marks)


I'll be around a bit this afternoon and then part of this evening to answer questions. Please post in this thread rather than sending me private messages.

Hi Mr M, just a quick few questions:

For 7(ii) is wasn't sure what to do so I wrote out the y-y1=m(x-x1) formula.
Then I calculated an answer for area under the tangent as a triangle (0.5 x base x height) which is incorrect.
Then Area of Triangle subtract Integration area given.
Any method marks gained here?

Also, 8(iv) Logs Question,
I got b=2/a
a^x = 4b^x
XLog2a = xlog2(4(2/a))
Xlog2a = xlog2(4) + xlog2(2) - xlog2(a)
Xlog2a = 2x - xlog2(a)
At which point i stopped.

Any marks gained here?
Thanks so much for the help!


Posted from TSR Mobile

yes

Hey Mr. M, thanks for the answers.
In question 4 I wrote +c instead of +k for the constant, does that mean I'll drop marks?
In question 8c) I said a=1, b=1/16 would a=1 be correct? You wrote a>1.
Finally (sorry for all the questions!) in question 9ii I divided f(x) by (2x+1) rather than showing f(-1/2)=0 and for some reason went on to get f(x)=(2x+1)^2(x+1), how many marks do you think I'd lose?

Thank you very much,
Amy

Hi Mr M, thanks for the answers!
Made a few silly slips, but I think I did okay! I have a few questions:

I accidentally found the perimeter for 5ii for the entire shape and not for BDC, will I gain any method marks?

For the integration question 7ii, I used y-y1=m(x-x1) to find the tangent, then integrated this and put the values of 4 and 5/2 into it. Then subtracted to get a positive area. Would I gain any method marks for this or is it completely incorrect?

I was also wondering whether you would have any idea of the grade boundaries?

Thank you!
Bethany

Mr M,

For question 2 I wrote my answers all to one decimal place instead of 3sf like you did, will I drop marks?
Also, for 9 part 2 I factorised it but didnt fully factorise the quadratic, how many marks would I lose?
Finally, for the area under the curve I explicitly stated that you had to use area of triangle but couldn't work it out, would I gain a mark?
Thanks

Hi Mr M,

I was just wondering, I did the Logs question a little bit differently to everyone else, but still got the same answer, but I was just wondering, do you get method marks for applying the Log laws in your working out?
Thanks.

For 9iii, I got 4 values but 3 of my values are correct. How much marks do I get for that question?
And for 7ii, I found out the area of the triangle under the line and then minused 9.5 from the area of triangle and got something like 1.1. I know this is wrong but how much marks would I get for calculating the area of triangle (if that was needed)?

Hi Mr M
On 3i) I wrote it in this order: 6000x^2 + 960x + 64 instead of '64 + 960x + 6000x^2
Wil I lose any marks?

And on 4b i) when integrating I wrote -12x^-2 + k. And then put the x^2 on the bottom to make -12/x^2. + k. Will I still get all the marks for this?

So worried

Hi Mr M,
For 8cii, I managed to show that, but i did it a long winded way taking logs of 10 and then changing the base to 2 near the end, it was all clear working and managed to get the correct solution though, how many marks would i lose?