[Mr M]

Mr M's OCR (not OCR MEI) Core 4 answers June 2012


1. (i) (2 marks)

(ii) (4 marks)


2. (5 marks)


3. (i) (6 marks)

(ii) (1 mark)


4. (6 marks)


5. (i) 60 degrees (2 marks)

(ii) (3 marks)


6. Show integration by substitution (7 marks)


7. (7 marks)


8. (a) -1 (4 marks)

(b) (i) (-1, 0) (3 marks)

(ii) or (3 marks)


9 (i) (5 marks)

(ii) (4 marks)


10 (i) Show (3 marks)

(ii) Show (4 marks)

(iii) 3 : 2 (3 marks)

[Doctor.]

Thank you once again

[a10]

isnt the first one suposed to be a minus not +? and how did u get 3:2 on the last question

[Mr M]

(Original post by Doctor.)
Thank you once again

You are welcome. I'm off home now but will be able to answer questions in about 45 mins so anyone can post here and I will deal with them in a bit.

[Doctor.]

Mr M,

I got


For question 4, would that be acceptable?

EDIT: Just read what you wrote Mr M, We'll we waiting!

[∫f(x)]

3i) Forgot to use 4x instead of x for last two terms. Would i get follow through for doing x(1+x^2) correctly?

ii) I just put 1/4, probably wont get the mark but meh

8b (i) I got t, but didnt put coordinate, how many marks will i lose?

[wibletg]

(Original post by a10)
isnt the first one suposed to be a minus not +? and how did u get 3:2 on the last question

He's changed the signs on the bottom of the equation

[Tateco]

(Original post by Mr M)
You are welcome. I'm off home now but will be able to answer questions in about 45 mins so anyone can post here and I will deal with them in a bit.

Thank you very much, on question 2 I arranged it in the by parts form but integrated x/(x+2) wrong, how many marks do you think that would lose me?

And for 1ii would you get any marks at all if you started taking them away from each other? (So made the denominators the same)

[Mr M]

(Original post by a10)
isnt the first one suposed to be a minus not +? and how did u get 3:2 on the last question

would be an alternative right answer for 1).

I got 3 :2 by finding the coordinates of B (-1, 0, 2) then finding the magnitude of OA as 3 sqrt 5 and the magnitude of OB as 2 sqrt 5.

[wibletg]

(Original post by Doctor.)
Mr M,

I got


For question 4, would that be acceptable?

EDIT: Just read what you wrote Mr M, We'll we waiting!

Double post - sorry.

It's exactly the same

[PhysicsMan]

Thank you.

For Q2, I got:

xln(x+2) + 2ln(x+2) - (x+2) + C

Is this not right? Because I substituted boundaries into the integral in the question and then my answer- and it turned out to be correct?

[a10]

(Original post by Mr M)
would be an alternative right answer for 1).

I got 3 :2 by finding the coordinates of B (-1, 0, 2) then finding the magnitude of OA as 3 sqrt 5 and the magnitude of OB as 2 sqrt 5.

i got 3 sqrt 5 but i didnt get 2 sqrt 5 hw many marks would i lose?

[awesomeness123]

I reckon I got around 58, any guesses at what the A boundary is gonna be?

[Sgt.Incontro]

Hi Mr. M,

What is your opinion on grade boundaries?

A*?
A?
B?...

etc.

Cheers.

[Notsocleverstudent]

(Original post by Mr M)
Mr M's OCR (not OCR MEI) Core 4 answers June 2012


1. (i) (2 marks)

(ii) (4 marks)


2. (5 marks)


3. (i) (6 marks)

(ii) (1 mark)


4. (6 marks)


5. (i) 60 degrees (2 marks)

(ii) (3 marks)


6. Show integration by substitution (7 marks)


7. (7 marks)


8. (a) -1 (4 marks)

(b) (i) (-1, 0) (3 marks)

(ii) or (3 marks)


9 (i) (5 marks)

(ii) (4 marks)


10 (i) Show (3 marks)

(ii) Show (4 marks)

(iii) 3 : 2 (3 marks)

This is a long one, sorry about this:

For Question 2, I showed how to do integration by parts, but used completely different u and v thingys, and I've checked in the past mark scheme and it awarded 0 marks for integration by parts if wrong u and v used
For question 3, I showed both the x^4 and x^5 terms
For question 4, I seperated the variables, intergrated whatever whatever, and got c=1/2
For question 10, i, i showed the 1st part only


How many marks dropped from all of this?

[lilipop]

Thank you!

[Doctor.]

(Original post by wibletg)
Double post - sorry.

It's exactly the same

Thanks dude

[Blurb12345]

Can anyone remember exactly what question 1) ii) was? I ended up with (6x -24) in the numerator which i then cancelled to get 6 over the two other terms that weren't (x-4). Not sure where I went wrong...

[Mr M (jr)]

(Original post by PhysicsMan)
Thank you.

For Q2, I got:

xln(x+2) + 2ln(x+2) - (x+2) + C

Is this not right? Because I substituted boundaries into the integral in the question and then my answer- and it turned out to be correct?

You've just got an extra "+2" which presumably you got by using a substitution to integrate x/(x+2). This is still correct, but you can "swallow up" any numbers into your constant. You should still get full marks.

[Dislocator]

Does anyone know what Question 8 actually was? Thanks!