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# Mr M's OCR (not OCR MEI) FP1 answers June 2012 Watch

1. (Original post by ninuzu)
Hi Mr M, thanks for these
For 9.(ii) your answer is 1/2(1, root3, -root3, 1). I halved everything and left it as a decimal so I got (0.5, 0.866, -0.866, 0.5) Would I still get the marks??

I'm trying to make the brackets look vaguely like a matrix there.
Also, for the shear question, I put a shear parallel to the x-axis scale factor 2, would that gain any marks?
Decimals in that matrix is fine.

You might drop a mark there. I haven't looked at a FP1 mark scheme for a few years so I don't know how fussy they are about language.
2. (Original post by Mr M)
Probably but not certainly.
Sorry I double posted now can't edit so ignore my other quote
3. Thank you again for the answers, I got one half of the matrix right and one half wrong for 9) ii) ? How many marks would I lose?
4. (Original post by Ugachaka)
Question 6 (ii) was (1/A - 1)(1/B - 1) where A and B are roots, i think? . I got the answer to this as 3, how did you get 8/5?
5. (Original post by Mr M)
Decimals in that matrix is fine.

You might drop a mark there. I haven't looked at a FP1 mark scheme for a few years so I don't know how fussy they are about language.
I also put this, they usually mention the term invariant but it means more or less the same thing :/
6. Mr M, could you post Question 6, what was the original quadrtatic?
7. (Original post by Mr M)
I think i might have overcomplicated the question, when you subsitute in the (1/u+1)? does this change the roots aswell?
8. yeah when you put 1/(u+1) the new roots are (1/x) -1 as that is the point of the substitution
9. for qs 6 , would you get a error carried forward for part ii?
10. (Original post by As_Dust_Dances_)
3/2 - 1/(n+1) - 1/(n+2) or something like that is what I got for 8ii)
This is correct and would get full marks.

Mr M is far too quick; some of us still have to teach! (A day of FP2 for me)

I can concur with all his (edited) answers. I would suspect that for Q4 n(n2+1) would get full marks, but can't guarantee it.
11. For the summation series question (first part) finding the sum to N, instead of simplifying the answer to 3/2 and the n stuff i put 1 + 1/2- 1/n+1 and the other n thing. Would i lose a mark?
12. (Original post by BenjaminKyle)
how many marks in total would i lose for stupidly drawing the loci |z|=|z-8| due to a misread (so that I ended up with a vertical line through (4,0) .... although i did do the circle and shade the right area of the circle correctly) - however i am worried i've made myself lose a lot of marks here as there was more than one part to the question dependent on the loci (such as the intercepts). Ahh i feel so ridiculous, this kind of problem never normally phases me, i honestly don't know what happened!
I'd imagine you would get carry on marks anyway, for drawing the wrong loci in the first place.
13. would you say this was a harder or easier than average paper? personally i thought the only tricky question was the induction Q which i could not do, but no one else seems to be fased by it.
14. for that induction question you have to do [SUM OF 4*3^k] + [4*3^(k+1)] since you have assume P(k) to be true you can then use it again
15. (Original post by crazymanny00)
for that induction question you have to do [SUM OF 4*3^k] + [4*3^(k+1)] since you have assume P(k) to be true you can then use it again
i did that but i couldn't get it into the right format. how many marks do you think i lost
16. Mr M,
I may have been a little bit silly and misread 6ii and thought that they were asking for (1/α -1) and (1/β -1) to be worked out separately. I worked these out to be:
-11/10 +- i root(39)/10

How many marks out of three do you think I would get?
Thanks
17. why was the rotation clockwise, because according to the formula book, its anticlockwise

because when you do cos -1 (0.5) you get 60 degrees so it must be 60 degrees anticlockwise
18. (Original post by KoalaKim)
why was the rotation clockwise, because according to the formula book, its anticlockwise

because when you do cos -1 (0.5) you get 60 degrees so it must be 60 degrees anticlockwise
You need to look at the sin part. -sin(60) = -0.866 when we wanted it to be positive in that position.

So the angle we are rotating anticlockwise must be -60
Hence 60 degrees clockwise
19. (Original post by TehCoolNerd)
You need to look at the sin part. -sin(60) = -0.866 when we wanted it to be positive in that position.

So the angle we are rotating anticlockwise must be -60
Hence 60 degrees clockwise
so why does the cos bit give you positive 60?

oh, i get it!!! how many marks will i loose???
20. (Original post by KoalaKim)
why was the rotation clockwise, because according to the formula book, its anticlockwise

because when you do cos -1 (0.5) you get 60 degrees so it must be 60 degrees anticlockwise
I double checked by drawing a diagram of the unit square under the transformation and it turns 60 degrees clockwise. That was also the formula I used

Updated: June 24, 2012
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