Answer:
The greatest common factor (GCF) of -16x^2 - 6x^4 is 2x^2.
To find the GCF, we can factor out the common factors of the two terms. In this case, both terms have a factor of 2 and a factor of x^2.
-16x^2 - 6x^4 = 2x^2(-8 - 3x^2)
So the GCF is 2x^2.