i need help solving these inequalities i'm not sure if i should factor things out or not

Question

4x^3 is greater than or equal to 16x

and

4 is greater than or equal to 2x^3 + 8x

Answer 1

Yes, you can factor out numbers which are positive as in equations.

4x>16 can be written as
x>4
(common factor 4 is positive.)

If the factor is negative, you can still factor it out, but you will need to reverse the sign of inequality.

-5x ≥ 40
x ≤ 40/(-5)
x ≤ -8
(common factor -5 is negative)

If the sign of the factor is unknown, then you'll have to make different cases:

ax > ab
x > b (if a>0)
x < b (if a<0)
x is undefined if a=0

Answer 2

-y-4+2y>11