Mr M's OCR (not OCR MEI) Core 1 Answers May 2013

For q4 I simplified it to 3 1/4 instead of 13/4 would I lose any marks? And for q5 if I read the question wrong, and moved the graph 4 in negative x and got 2/(x+4)^2 how many marks would I lose?

Also is the correct sketch for the _)|(_ something like that? Again q5
As the grade boundaries haven't changed since june12 61/72 for a and 54/72 for , what would you expect?


Thank you!

Mr M's OCR (not OCR MEI) Core 1 Answers May 2013


1. (i) $12 \sqrt 5$ (2 marks)

(ii) $4 \sqrt 5$ (1 mark)

(iii) $5 \sqrt 5$ (1 mark)


2. $x=\frac{1}{2}$ or $x=-1$ (5 marks)


3. (i) $f'(x)=2-\frac{12}{x^3}$ (3 marks)

(ii) $f''(x)=\frac{36}{x^4}$ (2 marks)


4. (i) $3(x+\frac{3}{2})^2+\frac{13}{4}$ (3 marks)

(ii) $(-\frac{3}{2}, \frac{13}{4})$ (3 marks)

(iii) $-39$ (2 marks)


5. (i) Correct sketch (2 marks)

(ii) $y=\frac{2}{(x+5)^2}$ (2 marks)

(iii) Stretch scale factor $\frac{1}{2}$ parallel to y axis (2 marks)


6. (i) Centre $(0, -4)$ and radius $2 \sqrt{10}$ (3 marks)

(ii) $(-2, -10)$ (2 marks)


7. (i) $x<-\frac{1}{8}$ (2 marks)

(ii) $0 \leq x \leq 5$ (5 marks)


8. $6x+2y-1=0$ (7 marks)


9. (i) Correct sketch with intersections at (-1.5, 0) and (2, 0) and (0, -6) (5 marks)

(ii) $x \leq \frac{1}{4}$ OR $x < \frac{1}{4}$ (either will be marked correct) (3 marks)

(iii) $4.5$ (4 marks)


10. (i) $k=-5$ (7 marks)

(ii) Minimum (2 marks)

(iii) $(-2, -27)$ (5 marks)


I'll be around to answer questions shortly.

Hi Mr m for question 7ii.
i left it has x<(equal to)5
how many marks would i drop?
Thanks

I would imagine only one mark.

Thanks what about if i divided by 2 on Q8?

How many marks would I get if I did the right curve but only in the first quadrant (i.e. I didn't put a second curve symmetrical to it on the opposite side of the y-axis)?

Mr M, for question 9 part ii) , I stated that the range of values was
-3/2 < x < 1/4 , I also go two solutions for the final question but had a line saying A = (-2,-27) as my final line of working (underlined). How many marks do you reckon I will lose?

Mr M's OCR (not OCR MEI) Core 1 Answers May 2013


1. (i) $12 \sqrt 5$ (2 marks)

(ii) $4 \sqrt 5$ (1 mark)

(iii) $5 \sqrt 5$ (1 mark)


2. $x=\frac{1}{2}$ or $x=-1$ (5 marks)


3. (i) $f'(x)=2-\frac{12}{x^3}$ (3 marks)

(ii) $f''(x)=\frac{36}{x^4}$ (2 marks)


4. (i) $3(x+\frac{3}{2})^2+\frac{13}{4}$ (3 marks)

(ii) $(-\frac{3}{2}, \frac{13}{4})$ (3 marks)

(iii) $-39$ (2 marks)


5. (i) Correct sketch (2 marks)

(ii) $y=\frac{2}{(x+5)^2}$ (2 marks)

(iii) Stretch scale factor $\frac{1}{2}$ parallel to y axis (2 marks)


6. (i) Centre $(0, -4)$ and radius $2 \sqrt{10}$ (3 marks)

(ii) $(-2, -10)$ (2 marks)


7. (i) $x<-\frac{1}{8}$ (2 marks)

(ii) $0 \leq x \leq 5$ (5 marks)


8. $6x+2y-1=0$ (7 marks)


9. (i) Correct sketch with intersections at (-1.5, 0) and (2, 0) and (0, -6) (5 marks)

(ii) $x \leq \frac{1}{4}$ OR $x < \frac{1}{4}$ (either will be marked correct) (3 marks)

(iii) $4.5$ (4 marks)


10. (i) $k=-5$ (7 marks)

(ii) Minimum (2 marks)

(iii) $(-2, -27)$ (5 marks)


I'll be around to answer questions shortly.

Hi Mr m for question 7ii.
i left it has x<(equal to)5
also for Q8) I divided by 2
how many marks would i drop?
Thanks

sorry to keep pestering you as you have been an amazing help, but how did you work out number 8 as again got something slightly different. thanks again

Mr M, for question 9 part ii) , I stated that the range of values was
-3/2 < x < 1/4 , I also go two solutions for the final question but had a line saying A = (-2,-27) as my final line of working (underlined). How many marks do you reckon I will lose?

How many marks would I get if I did the right curve but only in the first quadrant (i.e. I didn't put a second curve symmetrical to it on the opposite side of the y-axis)?

For K=-5 I worked it out to be -49 I did all the correct working but I put in a negative sign instead of a positive infront of K at one point. I multiplied out the brackets and found dy/dy made it equal to 0 and substituted -3 for x.

Then because this answer was wrong I couldn't do (-2,-27) I did the correct working but stopped when I couldn't find the multiples (because it didn't work) although I did do simultaneous equations and then showed an alternative method of dy/dx up until that point..

Is it possible to get any method marks and if so could you hazard a guess at how many marks I'll lose/get.. Thanks!! I got nearly full marks in the rest of the paper I'm just worried the wrong sign will cost me an A (((((

Will I lose marks for not not writing the differentiation answers in a more suitable format? For example I wrote 36x^-4 instead of 36 over x^4 and the same with the other differentiation question.