De Moivre's Theorem and quadratics

a) Find all solutions of the equation. (Write your answers in the form *a* + *b**i*. Enter your answers as a comma-separated list.)

http://www.webassign.net/latexImages...a439b3a7cf.gif

Answers I got for this is -2 + 2i and -2-2i..I assume you just use the quadratic formula and solve..is that right?

b) Find the indicated power using De Moivre's Theorem. http://www.webassign.net/latexImages...427f415f3e.gif

Don't know if I did it right, but I got 1024i for this problem..can someone verify?

Please help me to find out,A problem on De Moivre`s theorem

First i apologize if i have posted at wrong place....

The problem is here:

Solve **x^8+x^5+x^3+1** by using De Moivre`s theorem

An example in my book might help(didnt helped me at at all)

x^4-x^3+x^2-x+1

Sol:

The equation can be written as

x^4-x^3+x^2-x+1 = (x^5+1)/(x+1)

Hence the required roots of x^5+1 = 0 are same as those of (x^4-x^3+x^2-x+1)(x^5+1)

The equation (x^5+1) gives x^5 = -1 or x = (-1)^1/5

(......and so on)

**Now what my trouble is how i can find equation like (x^5+1) for my problem stated at start of post?**

*I am newbie and poor in maths so little more explanation will help lot*