I need to find all real and imaginary roots of this equation:

$\displaystyle 2x^7 - 2x^6 + 7x^5 - 7x^4 - 4x^3 + 4x^2 = 0$

Using synthetic division, I found that 1 is a root.

$\displaystyle (x - 1)(2x^6 + 7x^4 - 4x^2) = 0$

I'm not really sure how to proceed from here. Could someone point me in the right direction?