How can we determine the sign of a polynomial Given a polynomial along with the information that it has no real roots, then how can we say then whether it is greater or less than zero?

Hint #1: If $y=f(x)$ is a polynomial function with no zeroes, does the graph of $f$ intersect/touch the $x$-axis?  (That is, will $f$ change its sign in its domain?)
Hint #2: If $y=f(x)$ is a polynomial function with no zeroes, and furthermore, $f(x_0) > 0$ for a particular $x_0$ in the domain of $f$, does this mean that $f(x) > 0$ for all $x$ in the domain of $f$?  (Similarly for the case when $f(x_1) < 0$ for a particular $x_1$ in the domain of $f$, does that mean that $f(x) < 0$ for all $x$ in the domain of $f$?)
