Complex number (2 problems)

[kkc133211]

Hello guys, I have some troubles on the 2 problems but I could not figure out any hint to tackle them. So, could you please guide me for some steps to solve the problem ?
For Q6, I have found out the z= cos [((2k+1)pi)/(2n+1)] + i sin [((2k+1)pi)/(2n+1)], where k = 0, 1, 2, ..., 2n. But how should I continue ?
For Q7, I have no related ideas on both part (a) and (b)......

 

[Steven G]

Please show us your work so we can guide you to the correct solution.

 

[Dr.Peterson]

For Q6, I have found out the z= cos [((2k+1)pi)/(2n+1)] + i sin [((2k+1)pi)/(2n+1)], where k = 0, 1, 2, ..., 2n. But how should I continue ?

That's a good start.

What is the sum of the roots of the equation?

For Q7, I have no related ideas on both part (a) and (b)......

What do you get if you multiply that expression by (x - 1)? (When you answer that question, you'll see why I asked it.)

Then, though I haven't worked through the whole problem, I suspect the product of roots may come into play.

It may also be useful to tell us what topics you have been learning, as this clearly is not beginning algebra.