f(x,y)=x^2+y^2-x^2y^2, f'=2x-2xy^2, f'=2y-2x^2y, 令它们等于0,联立解,在D域内得驻点 (0,0), (1,1), (-1,1).f(0,0)=0, f(1,1)=1, f(-1,1)=1,；弧边界点 y^2=4-x^2, f(x) = 4-x^2(4-x^2)=4-4x^2+x^4=(x^2-2)...
f(x,y)=x^2+y^2-x^2y^2, f'=2x-2xy^2, f'=2y-2x^2y, 令它们等于0,联立解,在D域内得驻点 (0,0), (1,1), (-1,1).f(0,0)=0, f(1,1)=1, f(-1,1)=1,；弧边界点 y^2=4-x^2, f(x) = 4-x^2(4-x^2)=4-4x^2+x^4=(x^2-2)...