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# Edexcel FP2 Official 2016 Exam Thread - 8th June 2016 watch

1. (Original post by SeanFM)
As in how becomes ?
Yes please, I know how you'd do it by long division but on the solution for the question they changed the numerator from (z-1) to (z+1) -2, so I was just wondering how you would use this technique please? Thanks
2. Can somone explain how:

e^ int P dx dy/dx + ( e^ int P dx *Py) = e^ int P dx * Q

d/dx( e^ int P dx *Q) = e^ int P dx *Q

is the integral of e^ int P dx - Pe^ int P dx +C ?
3. Does anyone know whether partial fractions like those in question 18 here http://madasmaths.com/archive/maths_..._questions.pdf could be in the exam, not seem them with quadratic powers before! Thanks
4. Think I'll do the *** **** madas fp2 next Monday and Tuesday

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5. (Original post by economicss)
Yes please, I know how you'd do it by long division but on the solution for the question they changed the numerator from (z-1) to (z+1) -2, so I was just wondering how you would use this technique please? Thanks
If we had then we can 'add 0' to the numerator like so:

= and then use that (a+b)/c = (a/c) + (b/c) to give
6. (Original post by SeanFM)
If we had then we can 'add 0' to the numerator like so:

= and then use that (a+b)/c = (a/c) + (b/c) to give
Thank you

7. Would anyone mind explaining the solution for this question? I cant understand how they have gone from the first line in the solution to the second. Thanks!
8. (Original post by lkara)

Would anyone mind explaining the solution for this question? I cant understand how they have gone from the first line in the solution to the second. Thanks!
It's integrating factors. Basically the DE is an exact DE.
9. Does anyone know a site that has all of the IAL F2 papers? thanks very much
10. Can anyone explain why for question one we don't differentiate the whole thing then put pi over 4 in ?in the mark scheme they just expanded cot then put then times it by the x - pi over 4. Just wondering why they didn't differiatiate both parts this time.
11. Attachment 542281542283

(Original post by Tcoupe)
Can anyone explain why for question one we don't differentiate the whole thing then put pi over 4 in ?in the mark scheme they just expanded cot then put then times it by the x - pi over 4. Just wondering why they didn't differiatiate both parts this time.
I just did the expansion of cotx (by differentiating and inputting pi/4), multiplied through by (x-(pi/4))

Edit: Didn't mean to send it twice just useless with this phone
Attached Images

12. I'm trying to differentiate (dy/dx) = (e^-z) * (dy/dz). Using the product rule you know differentiating gives you (e^-z) * (the derivative of (dy/dz) with respect to x) + (dy/dz) * (the derivative of (e^-z) with respect to x) but I'm unsure how to differentiate something in terms of z with respect to x. I'd imagine it would be similar to implicit differentiation and I've gotten close to the right answer just playing around with the derivatives but I don't understand the maths behind it.

Thanks for any help/explanation/tips and sorry for the formatting.
13. (Original post by Patrick2810)
Does anyone know a site that has all of the IAL F2 papers? thanks very much
There are only two but try this

http://qualifications.pearson.com/en...nit%2FPaper-F2
14. (Original post by Xabier)
I'm trying to differentiate (dy/dx) = (e^-z) * (dy/dz). Using the product rule you know differentiating gives you (e^-z) * (the derivative of (dy/dz) with respect to x) + (dy/dz) * (the derivative of (e^-z) with respect to x) but I'm unsure how to differentiate something in terms of z with respect to x. I'd imagine it would be similar to implicit differentiation.

Thanks for any help/explanation/tips and sorry for the formatting.
I think (someone correct me if I'm wrong) with the derivative of e^-z it's, like you said, similar to implicit differentiation so you get
-e^-z (dz/dx).
With the derivative of (dy/dz) with respect to x, you want to get an expression that means (d^2y/dz)*(d/dx) so I think it becomes (d^2y/dz^2)*(dz/dx)?
15. (Original post by PhysicsIP2016)
I think (someone correct me if I'm wrong) with the derivative of e^-z it's, like you said, similar to implicit differentiation so you get
-e^-z (dz/dx).
With the derivative of (dy/dz) with respect to x, you want to get an expression that means (d^2y/dz)*(d/dx) so I think it becomes (d^2y/dz^2)*(dz/dx)?
I think the derivative of (dy/dz) would just be (d^2y/dz^2)

Or at least that's what I've been doing with the exam questions and it usually works out
16. (Original post by somevirtualguy)
I think the derivative of (dy/dz) would just be (d^2y/dz^2)
But it's with respect to x?
17. (Original post by PhysicsIP2016)
But it's with respect to x?
18. (Original post by PhysicsIP2016)
I think (someone correct me if I'm wrong) with the derivative of e^-z it's, like you said, similar to implicit differentiation so you get
-e^-z (dz/dx).
With the derivative of (dy/dz) with respect to x, you want to get an expression that means (d^2y/dz)*(d/dx) so I think it becomes (d^2y/dz^2)*(dz/dx)?
Thanks, just checked and your right on both.
19. (Original post by Zacken)
It's integrating factors. Basically the DE is an exact DE.

Thanks for your reply. I think I understand now. Would you mind checking the first few lines of my working to see if the logic follows?
20. (Original post by lkara)

Thanks for your reply. I think I understand now. Would you mind checking the first few lines of my working to see if the logic follows?
Perfect.

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