FP1 June 11 Edexcel - Paper and Model answers in the FIRST post.

As I have just edited my post to say, this seems very roundabout for what can only be 1 or 2 marks of a 4 mark question.
And there is the problem of + or - with this method which gets even more long-winded

I agree, but the mark schemes penalise you if you just quote dy/dx = 1/t

I shouldn't lose any marks for leaving my answer to 2c as below, right?

$z_2, z_3 = 5 \pm i\sqrt{3}$

Phew, I was starting to get a bit worried even though I meant exactly what Arsey had written.

Although it does say answers in the question! Arsey, any opinions?

yes

you have changed $7^{2k-1}$ to $7^{2k}$ in the third line

and the last line of working is all kinds of wrong

Oh yeah :|. I didn't see that ergghhh

Okay so it should be:

7(7^2k) - 7^-1(7^2k)
= 7(7^2k) - 1/7(7^2k)
=48/7(7^2k)

and then how do I show thats divisible by 12?

So would I get any method marks for that question based on what I've done?

Hopefully 100 this makes me feel marginally better about the dream-crusher that was C4

Oh yeah :|. I didn't see that ergghhh

Okay so it should be:

7(7^2k) - 7^-1(7^2k)
= 7(7^2k) - 1/7(7^2k)
=48/7(7^2k)

and then how do I show thats divisible by 12?

So would I get any method marks for that question based on what I've done?

y^2 = 48x
y = root(48)x^0.5
dy/dx = 0.5root(48)x^-0.5
dy/dx = 2root(3)/root(x)
then sub x = 12t^2

You can awlog that Im(z2)>Im(z3)

Also the solution to 9b) should read f(k+1)=49f(k) - 20X12 rather than + 20X12

You should then really show that 49f(k)>240 but probably unnecessary as f(n) is clearly increasing. I do induction a different way anyway.

I'm also wondering how you do 8 b) well without implicitly differentiating as that surely is not part of the FP1 syllabus. Maybe you can just assume that for a parabola dy/dx = 1/t. lOf course you can rearracnge for y, differentiate wrt x and then substitute t but that seems very roundabout

You can awlog that Im(z2)>Im(z3)

I can not remember what you did up to that point but you could say

$48 \times 7^{-1}(7^{2k})$

$12 \times [4(7^{2k-1})]$

hence divisible by 12

MagicMan - I have no idea what you mean by

MagicMan - I have no idea what you mean by



I realise I made a transcription error putting a + instead of a - in the final line of working, it has been mentioned quite a few times

The method given by Soapy is the intended method for this question but implicit is a lot quicker.

Will I lose any marks on the proof by induction question, for the one where you prove it's divisible by 12.

I stupidly left it as just 48 [ can't remember ]

Should I have changed it to 12 [ 4 x can't remember ] ?

how the **** do you access the first post