x^4 - 7 = 6x^2

I get this far:

x^4 - 7 = 6x^2

x^4 + 0x^3 - 6x^2 + 0x - 7 = 0

Factors of -7:

+/- 1, +/- 7

I don't know where to go from this point.

The homework relates to solving polynomial equations using factor/remainder theorem. Can someone please help?