Mr M's OCR (not OCR MEI) Core 4 answers 18th January 2013 Watch

Hazofhorsham
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For the integration by substitution (out of 7) how many marks do you think I'd get if I did everything correct but made a mistake integrating the second term? 4ish sound alright?
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Mr M
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(Original post by Hazofhorsham)
For the integration by substitution (out of 7) how many marks do you think I'd get if I did everything correct but made a mistake integrating the second term? 4ish sound alright?
Might even be 5.
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Coolina133
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(Original post by Mr M)
Mr M's OCR (not OCR MEI) Core 4 answers 18th January 2013


1. \frac{3x\sin(3x)+\cos(3x)}{9}+k (4 marks)


2. 27-72x+32x^2 and |x|<\frac{9}{16} (5 marks)


3. \frac{dy}{dx}=\frac{2x-y^2}{2xy}

Coordinates (1, \sqrt{2}) and (1, -\sqrt{2}) (7 marks)


4. (i) Show intersection and (5, 4, 6) (5 marks)

(ii) 68.2 degrees (3 marks)


5. (i) (\frac{19}{5}, -\frac{3}{5}) (5 marks)

(ii) 4(x-2)^2 + 9(1-y)^2 = 36 (2 marks)


6. -\frac{23}{384} (7 marks)


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

(ii) \ln (2+\sqrt3) (3 marks)


8. (i) Show ... (2 marks)

(ii) \begin{pmatrix} 3 \\ 2 \\ 1 \end{pmatrix} + \lambda \begin{pmatrix} 0 \\ 3 \\ -1 \end{pmatrix} or any other correct equation (3 marks)

(iii) Show ... (1 mark)

(iv) Kite (1 mark)


9. (i) \theta = -20 + C e^{-kt} (3 marks)

(ii) k=\frac{1}{20} and t = 22 minutes (5 marks)

(iii) k is greater in the second case (1 mark)


10. x-1+\frac{x+7}{x^2-x-6} (4 marks)

(ii) 8+ \ln (\frac{27}{4}) (7 marks)
Thanks for the answers mr m..
Basicay, with 3, i got the correct answer but i didnt expand my brackets so i left it as((x-2)/3)2 +((1-y)/2)2, will i lose a mark for not simplifying even tho it never specified to?
Also with 9, in the first bit i forgot to put the constant, and in the second part, i got the wrong constant as i forgot to add 20 so ln40 was my c. My method is all right and my k is right 2. How many marks do you think i will lose? In these questions?
Everything else seems okay and ive worked out to have got like 59-60. Do you think thats an a?


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Mr M
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(Original post by Coolina133)
Thanks for the answers mr m..
Basicay, with 3, i got the correct answer but i didnt expand my brackets so i left it as((x-2)/3)2 +((1-y)/2)2, will i lose a mark for not simplifying even tho it never specified to?
Also with 9, in the first bit i forgot to put the constant, and in the second part, i got the wrong constant as i forgot to add 20 so ln40 was my c. My method is all right and my k is right 2. How many marks do you think i will lose? In these questions?
Everything else seems okay and ive worked out to have got like 59-60. Do you think thats an a?


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The one you call 3) which is actually 5) is ok if that is an equation that is equal to 1 rather than the expression you posted.

Drop 3 marks on 9) overall?

I should think that is an A but no-one knows for sure at this stage.
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Coolina133
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Oh yeah and also in 3, i only got coordinates (1,root 2) as i didnt put +\- root 2.


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Mr M
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(Original post by Coolina133)
Oh yeah and also in 3, i only got coordinates (1,root 2) as i didnt put +\- root 2.
Drop 1 or 2 depending on how the marks are allocated in the scheme.
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Coolina133
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(Original post by Mr M)
Drop 1 or 2 depending on how the marks are allocated in the scheme.
Thank you so much


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Hazofhorsham
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Thanks Mr M One last question, on 7ii) I stated sec(x)=Cosx^-1, and subbed in Pi/3 and 0. But for some stupid reason I misread ln(cosx) as cosx the second time round so I got:

Ln(1+.5Root(3)) -ln(.5) -(ln1 -cos0)

Ln(1+.5root(3)) -ln(.5) -0 +1

Ln(2+root(3)) +1 and because we had to simplify to one log, I wrote:

Ln(2e +eRoot(3))

How many marks do you think I'll lose? 1,2 or all 3 of them?

Thank you
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XingBairong
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Hmmmm
I misread the formula book
I'm such idiot :l
So I did integration for sec^2 rather than sec
Do you reckon they will be benevolent and give me 1 Mark? T_T
I seems to lose 11 marks so probably have to retake in summer for A* Errrr!!

Thank you Mr M for the answers.
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MasonRP
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would i get away with putting rhombus?? and i reckon about 90% hopefully ums will scale that up a little :P
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MasonRP
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(Originally Posted by Coolina133)
Oh yeah and also in 3, i only got coordinates (1,root 2) as i didnt put +\- root 2.



i did the same i deliberately rules the second one out.. how annoying!
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jamesisenglish
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Mr M, how many marks do you think I would lose if, on Q3, I had my equations right, but misread them as "y=2x" and then ended up with (1,2) and (-1,-2)?
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Mr M
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(Original post by MasonRP)
would i get away with putting rhombus?? and i reckon about 90% hopefully ums will scale that up a little :P
No sorry.
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Mr M
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(Original post by jamesisenglish)
Mr M, how many marks do you think I would lose if, on Q3, I had my equations right, but misread them as "y=2x" and then ended up with (1,2) and (-1,-2)?
Drop 2 marks?
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Mr M
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(Original post by Hazofhorsham)
Thanks Mr M One last question, on 7ii) I stated sec(x)=Cosx^-1, and subbed in Pi/3 and 0. But for some stupid reason I misread ln(cosx) as cosx the second time round so I got:

Ln(1+.5Root(3)) -ln(.5) -(ln1 -cos0)

Ln(1+.5root(3)) -ln(.5) -0 +1

Ln(2+root(3)) +1 and because we had to simplify to one log, I wrote:

Ln(2e +eRoot(3))

How many marks do you think I'll lose? 1,2 or all 3 of them?

Thank you
I'm not sure you will get any more than 1 mark for that, sorry!
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Mr M
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(Original post by XingBairong)
Hmmmm
I misread the formula book
I'm such idiot :l
So I did integration for sec^2 rather than sec
Do you reckon they will be benevolent and give me 1 Mark? T_T
I seems to lose 11 marks so probably have to retake in summer for A* Errrr!!

Thank you Mr M for the answers.
I don't think you will get a mark for that sorry!

And you are welcome.
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Hazofhorsham
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Thank you
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jordantic
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(Original post by Mr M)
Mr M's OCR (not OCR MEI) Core 4 answers 18th January 2013


1. \frac{3x\sin(3x)+\cos(3x)}{9}+k (4 marks)


2. 27-72x+32x^2 and |x|<\frac{9}{16} (5 marks)


3. \frac{dy}{dx}=\frac{2x-y^2}{2xy}

Coordinates (1, \sqrt{2}) and (1, -\sqrt{2}) (7 marks)


4. (i) Show intersection and (5, 4, 6) (5 marks)

(ii) 68.2 degrees (3 marks)


5. (i) (\frac{19}{5}, -\frac{3}{5}) (5 marks)

(ii) 4(x-2)^2 + 9(1-y)^2 = 36 (2 marks)


6. -\frac{23}{384} (7 marks)


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

(ii) \ln (2+\sqrt3) (3 marks)


8. (i) Show ... (2 marks)

(ii) \begin{pmatrix} 3 \\ 2 \\ 1 \end{pmatrix} + \lambda \begin{pmatrix} 0 \\ 3 \\ -1 \end{pmatrix} or any other correct equation (3 marks)

(iii) Show ... (1 mark)

(iv) Kite (1 mark)


9. (i) \theta = -20 + C e^{-kt} (3 marks)

(ii) k=\frac{1}{20} and t = 22 minutes (5 marks)

(iii) k is greater in the second case (1 mark)


10. x-1+\frac{x+7}{x^2-x-6} (4 marks)

(ii) 8+ \ln (\frac{27}{4}) (7 marks)
DO you have the question paper?
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mitymiget
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(Original post by Mr M)
Mr M's OCR (not OCR MEI) Core 4 answers 18th January 2013


1. \frac{3x\sin(3x)+\cos(3x)}{9}+k (4 marks)


2. 27-72x+32x^2 and |x|<\frac{9}{16} (5 marks)


3. \frac{dy}{dx}=\frac{2x-y^2}{2xy}

Coordinates (1, \sqrt{2}) and (1, -\sqrt{2}) (7 marks)


4. (i) Show intersection and (5, 4, 6) (5 marks)

(ii) 68.2 degrees (3 marks)


5. (i) (\frac{19}{5}, -\frac{3}{5}) (5 marks)

(ii) 4(x-2)^2 + 9(1-y)^2 = 36 (2 marks)


6. -\frac{23}{384} (7 marks)


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

(ii) \ln (2+\sqrt3) (3 marks)


8. (i) Show ... (2 marks)

(ii) \begin{pmatrix} 3 \\ 2 \\ 1 \end{pmatrix} + \lambda \begin{pmatrix} 0 \\ 3 \\ -1 \end{pmatrix} or any other correct equation (3 marks)

(iii) Show ... (1 mark)

(iv) Kite (1 mark)


9. (i) \theta = -20 + C e^{-kt} (3 marks)

(ii) k=\frac{1}{20} and t = 22 minutes (5 marks)

(iii) k is greater in the second case (1 mark)


10. x-1+\frac{x+7}{x^2-x-6} (4 marks)

(ii) 8+ \ln (\frac{27}{4}) (7 marks)
Hello Mr. M! How would you go about working out Question 9?
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souljarb
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(Original post by mitymiget)
Hello Mr. M! How would you go about working out Question 9?
does anyone have the question paper for OCR core 4 jan 2013.

Thanks in advance
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