[size=85] Drag point [b][color=#980000]B [/color][/b]to generate [b][url=https://en.wikipedia.org/wiki/Contour_line]contour lines[/url][/b]. Their patterns will help you locate the local extrema of the function [b]f(x,y)[/b].[br] Move point [b]A[/b] to [color=#ff0000]display[/color] the [b][color=#333333]nxo[/color][/b] points of the [color=#ff7700]square[/color] with side length [b]ao[/b] on the surface of the function [b]f(x,y)[/b]. Below the plot on the left side, you will find the corresponding coordinates, as well as the maximum and minimum values of the function among these points ([b][color=#ff00ff]Rmax [/color][color=#333333]and[/color][color=#ff00ff] [b][color=#1e84cc]Rmin[/color][/b][/color][/b]) .[/size]