Welcome to the forum.
Are you sure you've posted the problem correctly? As it stands, I can't see how the latter statement is true. We have:
and sosince obviously But then the problem statement suggests that we should then have whereas the polynomial doesn't have any real roots. (You can show this by differentiating it once to find the stationary point, then again to show that it's a minimum -- then showing that at this minimum, is strictly positive, i.e. doesn't ever cut the x-axis.)]]>]]>