1. The problem statement, all variables and given/known data Find all complex numbers z such that z^6 = -64 2. Relevant equations I tried it in two ways, once with the sum of cubes (a + b)(a^2 - ab + b^2) as well as turning it into polar form and attempting it that way, z = re^(iθ) 3. The attempt at a solution I completely couldn't solve it at all with the sum of cubes, however, I managed to get six solutions by using the polar form and then saying that θ = ∏/3 (3 + k), where k = 0, 1, 2, 3, 4, 5 By subbing in k into the equation z = r(cosθ + isinθ), where r = 2, I get the answers: -2i, +-(-1 - sqrt(3)i), +- (1 + sqrt(3)i), and +2i. However, the book i'm using gives the answers +- 2i, and +- (sqrt(3) + i), and +- (-sqrt(3) - i). Thank you guys in advance.