1. What happens when the coefficient of x2 is NEGATIVE?

The parabola will be inverted or upside down.

2. What sort of graph has an x2 AND a y2 term?

This type of relation is usually a circle or an ellipse (flattened circle or oval shape)

3. What type of graphs are square root functions e.g. y = √x?

The shape of this graph is one half of a parabola on its side.