Let $H = f _ { x x } ( a , b ) f _ { y y } ( a , b ) - f ^ { 2 } x y ( a , b )$
What condition on H guarantees that f has a relative extremum at the point $( a , b )$

Question

Let $H = f _ { x x } ( a , b ) f _ { y y } ( a , b ) - f ^ { 2 } x y ( a , b )$  
What condition on H guarantees that f has a relative extremum at the point $( a , b )$

Quizplus · Accepted Answer

The Answer of Let $H = f _ { x x } ( a , b ) f _ { y y } ( a , b ) - f ^ { 2 } x y ( a , b )$  
What condition on H guarantees that f has a relative extremum at the point $( a , b )$

Let H=fxx(a,b)fyy(a,b)−f2xy(a,b)H = f _ { x x } ( a , b ) f _ { y y } ( a , b ) - f ^ { 2 } x y ( a , b )H=fxx​(a,b)fyy​(a,b)−f2xy(a,b)

Let $H = f _ { x x } ( a , b ) f _ { y y } ( a , b ) - f ^ { 2 } x y ( a , b )$