# Math Help - graphing help

1. ## algebra and trigonometry with analytic geometry problem

If f(x)=x(x+3)(x-1), use interval notation to give all values of x where f(x)>0. My answer would be (0,1) u (3,infinity) but not sure. thanks for checking.

2. Originally Posted by kwtolley
If f(x)=x(x+3)(x-1), use interval notation to give all values of x where f(x)>0. My answer would be (0,1) u (3,infinity) but not sure. thanks for checking.
The roots of $f(x)$ are: $-3,\ 0,\ 1$. $f(x)$ goes to $+\infty$ as $x \to \infty$ and
to $-\infty$ as $x \to -\infty$, so the set of values for which $f(x)>0$ is:

$
(-3,0) \cup (1,\infty)
$

RonL