Question 48097
f(x)=x(x+1)(x-4), 
your answer is incorrect because when x= 0 or -1 or 4, f(0)=f(-1)=f(4)=0
for the trigonomial f(x)to be positive(>0)
the three factors in this trigonomial x,(x+1),(x-4) should be
1)all three are positive, their product is positive.
2)two are negative and one positive, their product is also positive.

ANS:  x>4     (x,(x+1),(x-4) all >0)
   or -1<x<0  ((x+1)>0 and x,(x-4)<0)