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# FP3 (Not MEI) - Friday June 1 2012, AM Tweet

Maths exam discussion - share revision tips in preparation for GCSE, A Level and other maths exams and discuss how they went afterwards.

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1. Re: FP3 (Not MEI) - Friday June 1 2012, AM
Not sure what you have done on question two but when you get to x^-1a^-1 then you just use the given result. Question 3 means "prove all elements are self inverse, still not sure how to tackle it.
2. Re: FP3 (Not MEI) - Friday June 1 2012, AM
(Original post by ElMoro)
For the June 11 paper, question 5 part ii: why must k = -1?

EDIT: Nevermind, I was being an idiot
For anyone who is not clear, this is so that it is in the form.

If then on the RHS it is a function of u as well.
Last edited by SecondHand; 31-05-2012 at 18:06. Reason: latex
3. Re: FP3 (Not MEI) - Friday June 1 2012, AM
Yeah, I think question 3 follows on from one as one is proving a specific element is self inverse, and three all of them.

I'm just going to hope that these kind of questions are either nice or not prominent in the exam tommorow...
4. Re: FP3 (Not MEI) - Friday June 1 2012, AM
For this question part (ii)

How is that first step justified; surely they're assuming the result there?
5. Re: FP3 (Not MEI) - Friday June 1 2012, AM
(Original post by ElMoro)
For this question part (ii)

How is that first step justified; surely they're assuming the result there?
For 3. ii) ?
They have removed the left x and the right y, to end up with in the middle, or .
6. Re: FP3 (Not MEI) - Friday June 1 2012, AM
write (xy)^n as xyxyxyxyxyxyxyxyxy and then take and x from the front and a y from the back and you are left with x(yxyxyxyxyxyxyxyxyx)y or x(yx)^n-1y
7. Re: FP3 (Not MEI) - Friday June 1 2012, AM
(Original post by Killjoy-)
For 3. ii) ?
They have removed the left x and the right y, to end up with in the middle, or .
Ohhhhh, I get it! Thank you!

Don't think i could think of that in an exam tbh

EDIT: Unfortunately, I've repped you too recently
8. Re: FP3 (Not MEI) - Friday June 1 2012, AM
(Original post by ElMoro)
Ohhhhh, I get it! Thank you!

Don't think i could think of that in an exam tbh

EDIT: Unfortunately, I've repped you too recently
That's alright.
Did you see my response to the question you asked about the roots on the tan equation?
9. Re: FP3 (Not MEI) - Friday June 1 2012, AM
Page 318 q12. Anyone care to help..?
10. Re: FP3 (Not MEI) - Friday June 1 2012, AM
12a)

Length = 22

12b)

Length of AB = 22
Length of OA =
length of OB =

Length of OB is a multiple of the direction vector
11. Re: FP3 (Not MEI) - Friday June 1 2012, AM
(Original post by SecondHand)
12a)

Length = 22

12b)

Length of AB = 22
Length of OA =
length of OB =

Length of OB is a multiple of the direction vector
Cheers - that's a very swish way of working out the position vector of B!
12. Re: FP3 (Not MEI) - Friday June 1 2012, AM
Is anyone else feeling majorly underprepared?
13. Re: FP3 (Not MEI) - Friday June 1 2012, AM
You have to be confident going in or there is no way you will be confident going out.
14. Re: FP3 (Not MEI) - Friday June 1 2012, AM
...who on earth is confident going out of an exam?
15. Re: FP3 (Not MEI) - Friday June 1 2012, AM
(Original post by Killjoy-)
That's alright.
Did you see my response to the question you asked about the roots on the tan equation?
Yep I did. Thanks for that as well (sorry I thought I replied to it before )
16. Re: FP3 (Not MEI) - Friday June 1 2012, AM
(Original post by Ree69)
...who on earth is confident going out of an exam?
I am for economics never maths tho
17. Re: FP3 (Not MEI) - Friday June 1 2012, AM
I'm just hoping the groups questions are relatively friendly :P
18. Re: FP3 (Not MEI) - Friday June 1 2012, AM
Jan 12 Q6iii. I've got the answer but I'm not quite sure why it makes sense. Could someone explain this to me?
19. Re: FP3 (Not MEI) - Friday June 1 2012, AM
(Original post by Ree69)
Jan 12 Q6iii. I've got the answer but I'm not quite sure why it makes sense. Could someone explain this to me?
You know a plane can be expressed parametrically with two direction vectors that lie on it.
(These vectors cannot be parallel - cannot be the same.)

In part i) you were asked to indirectly find the normal to the plane.
Now recall that the vector product of two direction vectors will give a direction vector that is perpendicular to both of them.

So the vector product of the normal to the plane and the direction vector after lambda should give c.

For a vector equation of a plane the two direction vectors in the plane may or may not be perpendicular, but the normal is obviously perpendicular to both of them in all forms of the vector equation, since these vectors lie in the plane.

I think there was another method to find c in the MS but I can't remember - I used the one above when doing the paper since it seemed quicker.
Last edited by Killjoy-; 31-05-2012 at 20:57.
20. Re: FP3 (Not MEI) - Friday June 1 2012, AM
(Original post by Killjoy-)
You know a plane can be expressed parametrically with two direction vectors that lie on it.
(These vectors cannot be parallel - cannot be the same.)

In part i) you were asked to indirectly find the normal to the plane.
Now recall that the vector product of two direction vectors will give a direction vector that is perpendicular to both of them.

So the vector product of the normal to the plane and the direction vector after lambda should give c.

For a vector equation of a plane the two direction vectors in the plane may or may not be perpendicular, but the normal is obviously perpendicular to both of them in all forms of the vector equation, since these vectors lie in the plane.

I think there was another method to find c in the MS but I can't remember - I used the one above when doing the paper since it seemed quicker.
Ahh... cheers
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