求z=e^(X-Y)(X^2-2Y^2)的极值
问题描述：
求z=e^(X-Y)(X^2-2Y^2)的极值
答
Fx(x,y)= e^(x-y)(x^2-2y^2)+e^(x-y)·2y=e^(x-y)·(x^2+2x-2y^2)=0 ①Fy(x,y)=- e^(x-y)(x^2-2y^2)+e^(x-y)·(-4y)=e^(x-y)·(x^2+4y-2y^2)=0 ②由 ①②得 驻点 为 (0,0) (-4,-2)A= Fxx(x,y)= e^(x-y)(x^2+2x-2y^2)...