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# AQA FP2 help needed Watch

1. Having trouble with question 8 on the AQA FP2 January 2012 paper, specifically part c and d. If anyone would be willing to help I would be extremely grateful.

Thanks
2. (Original post by IMZL)
Having trouble with question 8 on the AQA FP2 January 2012 paper, specifically part c and d. If anyone would be willing to help I would be extremely grateful.

Thanks
What have you tried?
3. (Original post by joostan)
What have you tried?
I haven't gotten far at all really. Only thing I can see is pairing z+1/z and z^2+1/z^2, to get 2cos2π/5 and 2cos4π/5?
4. (Original post by joostan)
What have you tried?
I just got part c I think. Using part b to multiply out corresponding linear factors( i.e. (z-e^2πi/5)(z-e^-2πi/5)) noticing e^-2πi/5+e^2πi/5=2cos2π/5 and dividing by z^2?
5. For part (d) find w^2 and see how you can write z^2 + z^(-2) in terms of only w and w^2 this should let you get a quadratic in w.
6. (Original post by Zacken)
For part (d) find w^2 and see how you can write z^2 + z^(-2) in terms of only w and w^2 this should let you get a quadratic in w.
Oh yeah, got it, thanks!
7. (Original post by IMZL)
I just got part c I think. Using part b to multiply out corresponding linear factors( i.e. (z-e^2πi/5)(z-e^-2πi/5)) noticing e^-2πi/5+e^2πi/5=2cos2π/5 and dividing by z^2?
This is correct, by the way. :-)

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