I need to find the zeros as well as see where it is positive or negative so that I can match it to a graph for a question. My only problem (from what I can tell so far) is how to find the zeros. When I find the zeros, I think I might be able to manage the rest:

-x^5 + 5x^3 - 4x

-x(x^4 - 5x^2 + 4) <--------------What do I do next?

Any help would be greatly appreciated!

Thanks in advance!