Yes, there's a point of inflexion if .
Bear in mind that gives the rate of change (with respect to x) of , the gradient of .
So when , , the gradient of the curve, is increasing; and when , is decreasing.
But when the gradient of goes from increasing to decreasing (or the other way round). This is what a point of inflexion is - where the tangent touches the curve and cuts it at the same time (in other words has 3-point contact).