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Homework Statement:
 Solving min max problem in 2 variables using Mathematica
Homework Equations:

(x + y)*Sin[x  y],
3 questions: how many min/max points in R^2 and how many "saddle points"(in 3d)?
Drawing the graph in 3d you see endless "mountains and valleys" which logic tells me there will also be infinite max min points in 2d regardless of where you slice the graph. apparently this is wrong and there is a finite max/min points in R^2/2D. Please note this problem does not have a domain.
f'x= (x + y) Cos[x  y] + Sin[x  y]==0
f'y =(x + y) Cos[x  y] + Sin[x  y]==0
fx==fy
y =(x)
f'x=sin2x==0 (infinite max min )
f'y=sin2y==0 (infinite max min)
....what am i doing wrong?
f'x= (x + y) Cos[x  y] + Sin[x  y]==0
f'y =(x + y) Cos[x  y] + Sin[x  y]==0
fx==fy
y =(x)
f'x=sin2x==0 (infinite max min )
f'y=sin2y==0 (infinite max min)
....what am i doing wrong?