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# OCR (not MEI) C1 - Wednesday 13th May 2015 watch

1. (Original post by Meray98)
Do you remember what you got for 8) part iii. It was the one about working out K when their was no real roots
K < -25/8
2. (Original post by andrewc23)
Can anyone remember how many marks the scale factor question was worth?. Also can someone explain briefly how on the K question the answer was -25/8
Think the scale factor question was 2, could have been 1 though. Doubt it would be worth more than this.
For the K question, you needed to move the K onto the side of the quadratic (can't remember the actual function in terms of numbers) then find the discriminant, b^2 - 4ac, which was 25 + 8k. This needed to be less than 0 since you were told there were no real roots, therefore 25 + 8k < 0 => 8k < -25 => 8k < -25/8.
Hope that helped.
3. Does anyone remember what they got for the points Q and R for Q8?

Was it (0, -2) and (0,8) or something like that?
4. (Original post by gabby07)
Does anyone remember what they got for the points Q and R for Q8?

Was it (0, -2) and (0,8) or something like that?
This was Q10 :P but yeah, (0,-2) for circle and (0,8) for tangent.
5. I found the paper easy, but apparently most people in my year said it was difficult?
6. (Original post by Alevelsssss)
Unofficial mark scheme!? Everyone add bits in or correct me
1) 4rt3 +4
2i) graph, ii) -1/(x-2) iii) stretch sf 3 parallel to y axis or 1/3 parallel to x axis
3i) 8 ii) -0.25 iii) 9/2
4) x=27 x=-8
5i) 5 ii) 6x-8y-29
6) x=2 x=14/3 y=1 y=-13/3
7a) -3x^2+10x-3 b) 1/48
8i) graph ii) x<-1 x>1.5
9i) a=13 ii) min iii) 1/3
10i) (5,-2) radius 5 ii) show iii) 40
Feel free to dispute, this is what I got though
can anybody remember what the actual questions were for question 4 and 5ii ??? I can't remember if I got these answers or not. Thank you!!
7. (Original post by andrewc23)
Can anyone remember how many marks the scale factor question was worth?. Also can someone explain briefly how on the K question the answer was -25/8
only 2 gg

maths help here if needed

Cheers guys
9. (Original post by gabby07)
Does anyone remember what they got for the points Q and R for Q8?

Was it (0, -2) and (0,8) or something like that?
Yes it was;

and for everyone asking, the last question could be done in two ways:

(1) it forms an isosceles triangle (sides of 10), base of root 80, and the height was also root 80, so therefore area was 0.5*root80*root80 = o.5*80 = 40

(2) Height was 8,(going along the x-axis), base was 10(going along the y axis) so 0.5*8*10 = 40.
10. Things I got wrong: finding K - but I used the discriminant, 10ii - completely wrong, 10iii - I got 94/4 and used (0.5*4*fraction + 0.5*8*other fraction) it was wrong but I found Y and one other correctly, 3iii - wrong, and half of simultaneous equation wrong.

Everything else I'm pretty sure I got correct. - what do you think my mark was????
11. what was the question for 4 and 5) iii again?
12. (Original post by chloe-jessica)
Think the scale factor question was 2, could have been 1 though. Doubt it would be worth more than this.
For the K question, you needed to move the K onto the side of the quadratic (can't remember the actual function in terms of numbers) then find the discriminant, b^2 - 4ac, which was 25 + 8k. This needed to be less than 0 since you were told there were no real roots, therefore 25 + 8k < 0 => 8k < -25 => 8k < -25/8.
Hope that helped.
Ok thank you. For the scale factor one was it one of those where you get a mark for saying stretched and one for 1/3. I'm trying to claw some marks back
13. (Original post by andrewc23)
Ok thank you. For the scale factor one was it one of those where you get a mark for saying stretched and one for 1/3. I'm trying to claw some marks back
I think so in the mark schemes from previous years it's always been stretch (1) scale factor and correct axis (1)
14. (Original post by chloe-jessica)
I think so in the mark schemes from previous years it's always been stretch (1) scale factor and correct axis (1)
i put stretched scale factor 3. So hopefully one there. I dropped all 3 on the K one. Then on 10 iii i got the coordinates but got 50units^2. Looking at the unofficial mark scheme i didnt get any others wrong so it looks like i may have dropped 7 overall so hopefully an A.
15. (Original post by gabby07)
Does anyone remember what they got for the points Q and R for Q8?

Was it (0, -2) and (0,8) or something like that?
yep and then the third coordinate was (8,2)
16. (Original post by andrewc23)
i put stretched scale factor 3. So hopefully one there. I dropped all 3 on the K one. Then on 10 iii i got the coordinates but got 50units^2. Looking at the unofficial mark scheme i didnt get any others wrong so it looks like i may have dropped 7 overall so hopefully an A.
Sometimes you end up with more marks than expected as they award method marks for a variety of things I personally can't see the A boundary being any higher than 65 though, so I'm sure you'll get the A.
can anybody remember what the actual questions were for question 4 and 5ii ??? I can't remember if I got these answers or not. Thank you!!
i think... not fully sure, but I think 5ii may have been the one where it was the equation through the midpoint of A and B?
18. Things I got wrong: finding K - but I used the discriminant, 10ii - completely wrong, 10iii - I got 94/4 and used (0.5*4*fraction + 0.5*8*other fraction) it was wrong but I found Y and one other correctly, 3iii - wrong, and half of simultaneous equation wrong.

Everything else I'm pretty sure I got correct. - what do you think my mark was????
19. (Original post by Alevelsssss)
Unofficial mark scheme!? Everyone add bits in or correct me
1) 4rt3 +4
2i) graph, ii) -1/(x-2) iii) stretch sf 3 parallel to y axis or 1/3 parallel to x axis
3i) 8 ii) -0.25 iii) 9/2
4) x=27 x=-8
5i) 5 ii) 6x-8y-29
6) x=2 x=14/3 y=1 y=-13/3
7a) -3x^2+10x-3 b) 1/48
8i) graph ii) x<-1 x>1.5
9i) a=13 ii) min iii) 1/3
10i) (5,-2) radius 5 ii) show iii) 40
Feel free to dispute, this is what I got though
7b was -1/48

k < - 25/8

a = 13

Area of triangle (Last question) = 40

Simutaneous equations pairs x = 2 y = 1, x = 14/3, y = -13/3

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