(a)

Observe the graph :

The solid point indicates that the point included in the function.

Hole point indicates that the point excluded in the function.

So the graph does not have minimum in the open interval.

(b)

Observe the graph :

The solid point indicates that the point included in the function.

Hole point indicates that the point excluded in the function.

So the graph has minimum in the open interval.

(a) The graph does not have minimum in the open interval.

(b) The graph has minimum in the open interval.