A quadratic programming problem seeks to maximize a quadratic objective function (with ter...

A quadratic programming problem seeks to maximize a quadratic objective function (with terms like  or 5x1x2) subject to a set of linear constraints. Give an example of a quadratic program in two variables x1, x2 such that the feasible region is nonempty and bounded, and yet none of the vertices of this region optimize the (quadratic) objective.