Posted by **m** on Thursday, September 8, 2011 at 4:58pm.

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

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

and

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

- algebra 2 -
**MathMate**, Sunday, September 11, 2011 at 9:41am
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

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