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

1. (Original post by Brian luiz)
Yes its stretch of scale factor 1/3 parallel to x axis
I'm probably being stupid but it was 1/x to 1/3x iirc therefore a stretch of (1/3) aka timing by 1/3 would give 1/3x?
2. (Original post by AlfieH)
A was 13 because..

1) Differentiate the equation which was y=2x^3-ax^2+8x+2 which gives 6x^2-2ax+8
2) Equate this to 0 for stationary point
3) Plug in x=4 which gives 6(16)-8a+8=0
4) Sort this out and rearrange etc to get 104=8a therefore 104/8=a which is 13/
I made the god-awful mistake of somehow getting 8x^2-2ax+8, and carried on through all the parts... How many marks do you reckon I'll drop?
3. Everyones saying 40 but I got 20 root 5??
4. (Original post by waseemsharif54)
Everyones saying 40 but I got 20 root 5??
100% 40sq units
5. Posted from TSR Mobile

Deffo 40. 10*8*0.5
6. (Original post by Rodgersd09)
I made the god-awful mistake of somehow getting 8x^2-2ax+8, and carried on through all the parts... How many marks do you reckon I'll drop?
Don't worry, I subtracted the 8 instead of plusing it and got a=11 and I couldn't find the other stationary point because of this mistake
7. (Original post by Parallex)
the third root of -8 to the power of 4 is equal to the third root of 8 to the power of 4, so the answers would be the same
Oh yes ofcourse. Silly my, i first put -1/48 as the answer because i used the substitution as x = 8 but then realised it was -8. Damn i forgot to change it lol
8. (Original post by User10102929)
Attachment 397237Not 100% sure this is right, but this is how I got 'stretch by 1/3 in y-axis'
This is exactly what I thought
9. (Original post by jt663)
I'm probably being stupid but it was 1/x to 1/3x iirc therefore a stretch of (1/3) aka timing by 1/3 would give 1/3x?
Ah im crap at transformations, you're probably right
10. (Original post by gabby07)
100% 40sq units

I must have worked out a length wrong then. Was point Q where the circle meets y axis (0,-2)?
11. Posted from TSR Mobile

Yeah and R was 0,8
12. (Original post by gabby07)
100% 40sq units
i wrote 40 then crossed it out,
will i get any method marks for working out the Q and R coordinates and writing area=.5x basex height ?
(q out of 4)
13. (Original post by waseemsharif54)
Everyones saying 40 but I got 20 root 5??
14. Was the radius of the circle 5? at the end
15. (Original post by ChoccyPhilly)
65/72 was unusually high for a core 1 exam. They're normally 61/62 and s1 and core 2 A marks are normally 56-59
Yeah, in comparison, 2014 was more straightforward than this one as lot of of people tripped up. It's normally low 60s, high 50s.
16. (Original post by Parallex)

thanks for that! I thought there was a right angle at point P which is why I didn't split into two triangles.
17. I got 40 square units
-1/48
stretch of 1/3 parallel to the y axis (can someone clarify on this please? not sure if right)
k<-25/8
18. looks like a stretch parallel to x scale factor 1/3 to me tbh

Attached Images

19. Posted from TSR Mobile

You still get the same answer cuz distance from y axis to P stays the same for both

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