Let me start from here.The four points given are (-2,0),(0,-2),(2,-1),(4,0).When you will plot these points on the coordinate axes and join all these points you will get the shape of a triangle.One line lies completely on x axis another two lies below x axis.These two lines intersect at (0,-2). Now this is the turning point of the curve because curve takes a turn from here.
The meaning of continuity is that there should be no breaking points in the function.But the function breaks at (-2,0),(0,-2)&(4,0).So at all these points function i.e triangular curve takes the turn.So this might be also the turning point.
