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

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.

any suggestions on why for the last part of question 10 i got (1,0)?! I differentiated the equation given then equated it to 9 assuming they would have the same gradient, as y=9x-9 was the tangent to the curve. lots of questions, sorry!

Mr M,

For the last question I got two coordinates for A instead of 1 , I got (0,-9) and (-2,-27)(the right answer) how many marks do you think I lost?
Thanks!

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.

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

think i got about 60-63? do you reckon this would be an a?

Hi Mr. M, I got the radius as $\sqrt{30}$ because I thought $16+24=30$ (no idea why), but I got the center and the next part right. Drop one mark? two?
Thanks!

Im guessing you probably got the wrong value of k like me. The correct value of k was -5

How many marks would you get on 10iii) if you got two set of coordinates including the correct set and no further working?

why cant you type them up, as i cant remember half of them. sorry for the inconvenience

Sorry to ask again just wondering if its drop a mark for $\sqrt{40}$ rather than $2\sqrt{10}$ on the circles radius ?

For Q4 I put 39/12 but didn't cancel it. Will I sti get full marks? Thanks.

No, that's fine.

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.