What is solution to Responding to challenge by the Cardassians?

I got f(x) = 4(x-1)^2 (x+3) / ((x+1)^ 4(x-3))It does not look totally correct at x =-4; on the graph it looks like y=.8 or something, but my f(-4) is like .04. they made another challenger and made that go in space also got a know crew and changed the mission