Example 3 -- Finding Local Extrema

f = 9 - 2x + 4y - x^2 - 4y^2 ;

Plot3D[f, {x, -4, 4}, {y, -2, 2}, AxesLabel {x, y, z}]

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ts = Table[t, {t, -2, 2, .5}] ;

RowBox[{Do, [, RowBox[{RowBox[{Plot3D, [, RowBox[{f, ,, {x, -4, 4}, ,, {y, -2, 2}, ,, PlotPoin ... RowBox[{-, 2.4}], ,, -ts[[t]]}], }}]}], ,, TicksNone}], ]}], ,, {t, 1, Length[ts]}}], ]}]

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ContourPlot[f, {x, -4, 4}, {y, -2, 2}, ContourShadingFalse, Contours20, PlotPoints15]

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Created by Mathematica  (December 11, 2003)