While plotting constraints on a graph paper, terminal points on both the axes are connected by a straight line because?

While plotting constraints on a graph paper, terminal points on both the axes are connected by a straight line because the constraints are linear equations or inequalities. An optimal solution is a feasible solution where the objective function reaches its maximum (or minimum) value – for example, the most profit or the least cost. A globally optimal solution is one where there are no other feasible solutions with better objective function values.