You can use the two sliders in this applet to move the endpoints, [math]\left( a, f\left(a\right) \right)[/math] and [math]\left( b, f\left(b\right) \right)[/math]. Notice the open circle at each endpoint, indicating that we're working on the open interval [math]\left( a, b \right)[/math].[br][br]Try to move the endpoints to create the following:[br][list][*]An open interval with a minimum and a maximum.[br][/*][*]An open interval with only a minimum.[br][/*][*]An open interval with only a maximum.[br][/*][*]An open interval with neither a minimum nor a maximum.[br][/*][/list]