Does this table represent a function? Why or why not

Acircle has a diameter will endpoints of (-2,8) and (6, 4). what is the center of the circle

The vertex of this parabola is at (-2,-3). when the x-value is -1, the y-value is -5. what is the coefficient of the squared expression in the parabola's equation?

Find the area of the region that is inside r=3cos(theta) and outside r=2-cos(theta). sketch the curves.