A graph that shows the relationship between two variables that have a maximum is shown by a line that starts out sloping upward,reaches a maximum,and then slopes downward. Figure A 1.3 illustrates such a relationship with curve B.
A graph that shows the relationship between two variables that have a minimum is shown by a line that starts out sloping downward,reaches a minimum,and then slopes upward. Figure A 1.3 illustrates such a relationship with curve A.