Posted by adrienne on Tuesday, March 26, 2013 at 11:25pm.
solve the polynomial inequality and graph the solution set on a real number line. set in interval notation.
x^3+2x^24x8>0
I have been staring at this problem for the last 15 minutes because I just don't understand it, somebody please help me?

math  Steve, Wednesday, March 27, 2013 at 11:28am
x^3+2x^24x8 > 0
(x+2)^2 (x2) > 0
Now, you know that the graph touches the xaxis at x = 2 and cross it at x=2
Since y<0 for large x<0, that means that y<0 for x < 2, and stays <0 up to x=2, where it crosses the xaxis.
So, the solution set is x>2