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OCR FP1 this afternoon..

I'm also unsure about the question where you had to work out 1/alpha+1/beta+1/gamma by using substituition method. I got 1/3 :s-smilie:

I think thats wrong thou... what did everyone else get?

Reply 21

Lili!

OP

1

I don't know if I want to see the answers! Haha, well I do. But y'know. I want to know the methods more than anything! Especially for that damn last question!

Also, for the first question (where you were given the modulus and argument of a number), did people get whole numbers for the values of a and b, or decimals? I got decimals so assumed it was wrong! :s-smilie:

Reply 22

Lili!

OP

1

schizoFan

I'm also unsure about the question where you had to work out 1/alpha+1/beta+1/gamma by using substituition method. I got 1/3 :s-smilie:

I think thats wrong thou... what did everyone else get?

I can't remember what I got but I found -b/a for the equation worked out in the previous question (after you subbed in 1/alpha).. I thought it was like finding the sum of the roots.. So used -b/a?

Reply 23

Lili!

OP

1

Schizofan, I didn't get the same but I think you're right!

Ugh.. Why didn't I think to do that?! My mind just totally went black, ha.

Well done though!

Reply 24

Drarren

1

Seemed to be a nice test. The induction was great, nothing too complicated.

I got -3 for the 1/alpha.... but I'm not sure if that's correct or not

I got four answers for the final question, but there were two identical pairs, so only two answers really. I was really lucky with it. I miss-read the question, and used 16 not 15, and found it was impossible to get a gd answer because there was this annoying +1, lol.

Reply 25

blue_n_white

schizoFan

This is what I did for the last question... Im not sure if its right thou! it seemed right at the time thou ha

I think the question was this: z²-2z-(15+30i)

Then by using completed the square….

= (z-1) ²-1-(15+30i)

= (z-1) ² -16 – 30i

=(z-1) ² = 16 + 30i

(z-1) = 5+3i [From the previous question]

z = 6+3i

OR

(z-1) = -5-3i [From the previous question]

z = -4-3i

anyone else get the same??

mmm i rekon i got it wrong i got

1 ^{+}_{-} \sqrt{34}i

haha, but by looking at urs u got it right i think.

...the rest i cud do tho :biggrin:

...xcept describe the transformation D for 3 marks

Reply 26

Drarren

1

I wasn't sure how to score 6 marks drawing argand diagrams, it seems so many marks for drawing a circle and a line.

Reply 27

blue_n_white

uve got to get them right tho havnt u, u have to recognise both are, for the circle- its midpoint and radius, and the line doesnt start at (0,0) and you have to hav the correct gradient

Reply 28

Lili!

OP

1

Must use a scale! Must use a scale! Must use a scale!

I chant that in my head every time I read "Draw an Argand Diagram.."!

I didn't realise it was 6 marks though.. think I got that one right! So yay, 6 marks at least!

Reply 29

100% Mathmo

In regards to the last question i got the answers -4 - 3i and 6 + 3i but i was a little confused thinking that there must be complex conjugates and therefore 4 answers. However, it was only a quadratic and so can only have 2 roots and so left it as that which i hope was right. I got that there was no solutions for the other question with 'a' what about everyone else?

Reply 30

Drarren

1

thats a gd point, I didn't think of the conjugates. I'm not sure if they would be correct, hope not, lol

Reply 31

100% Mathmo

Yeah! About the argument part of the argand diagram question, did you need to put a circle around the point (i think it was 1) to show that it was not included in the line? I did as i had read something about the circle in quick last minute revision before the exam but didn't have time to check it out. Did anyone else do the same?

Right comrades heres the answers to OCR FP1 (not MEI)

1. a = 2 b = 2 root 3 (4 marks)

2. Proof by induction (5 marks)

3. Show = n^3 (6 marks)

4. (i) Inverse of A = top row (2.5 -0.5) bottom row (-1.5 0.5) (2 marks)

(ii) (AB)^-1 = top row (1 0) bottom row (11.5 -2.5) (4 marks)

5. (i) Show .. (1 mark)

(ii) n/(n+1) (3 marks)

(iii) 1/(n+1) (3 marks)

6. (i) (a) alpha + beta + gamma = 3
alphabeta + betagamma + gammaalpha = 2 (2 marks)

(b) alpha^2 + beta^2 +gamma^2 = 5 (2 marks)

(ii) (a) 2u^3+6u^2-9u+3=0 (2 marks)

(b) 1/alpha + 1/beta + 1/gamma = -3 (2 marks)

7. (i) det M = a^2 -12a + 32 (3 marks)

(ii) a=2 non singular as det M does not equal 0 (it equals 12) (2 marks)

(iii) a=4 det M=0 equations are inconsistent no solutions (3 marks)

8. (i) draw a circle centre 3 + 0i radius 3
draw a half line starting from 1 + 0i at 45 degs (6 marks)

(ii) shade part of circle bounded by line at 45 degs, the real axis and the circle (2 marks)

9. (i) A = (root 2 0) top row (0 root 2) bottom row (1 mark)

(ii) rotation clockwise about O by 45 degs (3 marks)

(iii) show C = AB (1 mark)

(iv) draw a unit square and a superimposed square with vertices at (0,0) (1,1) (2,0) (1, -1) (2 marks)

(v) Det C = 2 so area scale factor is 2 (2 marks)

10. (i) square roots are 5 + 3i and -5-3i (6 marks)

(ii) z = 6 + 3i or z = -4 + 3i (5 marks)

I'll leave you cheering or screaming... back on thursday with core 4 answers

Mr M.

Reply 33

Lili!

OP

1

Ahaha. I think a re-take is on the cards.

Reply 34

sam1990

are you sure question one isn't a = 1 b = root3

Reply 35

furdermatt_steeeee

Hiya every1, I'm new to this and this is my first post ever! I'm in year 12 (just finishing...got D1 on thursday and then I have finished A/S)....

I thought this paper was a lot nicer than I was expecting, answered everything but had little time to check over at the end, I naturally left the induction question to the end cos I have this strange phobia of them and inevitably I ended up trying to 'fiddle' the answer to make it look right as I had little time at the end, I am hoping for a strong A overall and I just hope this paper (which I consider my weakness) has not let me down...

hope everyone is alright,

steve aka steeee

sorry sam my answer was correct

Reply 37

sam1990

Darn you Mr M, with your god like mathematical ability, lol i had hope for a while

otherwise I have 58/72, mite get sum method marks along the way for some of the other ones

Reply 38

100% Mathmo

Yeah i got that for question 1 but can't quite remember what i put for question 6, is it possible to have the written question for this one?
Overall i though it was quite a nice paper and am glad there were only 2 roots for the last question like some others!

Reply 39

sandeep18

schizoFan

This is what I did for the last question... Im not sure if its right thou! it seemed right at the time thou ha

I think the question was this: z²-2z-(15+30i)

Then by using completed the square….

= (z-1) ²-1-(15+30i)

= (z-1) ² -16 – 30i

=(z-1) ² = 16 + 30i

(z-1) = 5+3i [From the previous question]

z = 6+3i

OR

(z-1) = -5-3i [From the previous question]

z = -4-3i

anyone else get the same??

yer, i got the same as you :smile:

OCR FP1 this afternoon..

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