y^(2/3)=a^(2/3)-x^(2/3)
由于x与y有对称性,不妨设y>0.
y=[a^(2/3)-x^(2/3)]^(3/2)
dy/dx=(3/2)*[a^(2/3)-x^(2/3)]^(1/2)*(-2/3)*x^(-1/3)
=-[a^(2/3)-x^(2/3)]^(1/2)*x^(-1/3)
=-(y/x)^(1/3)
y^(2/3)=a^(2/3)-x^(2/3)
由于x与y有对称性,不妨设y>0.
y=[a^(2/3)-x^(2/3)]^(3/2)
dy/dx=(3/2)*[a^(2/3)-x^(2/3)]^(1/2)*(-2/3)*x^(-1/3)
=-[a^(2/3)-x^(2/3)]^(1/2)*x^(-1/3)
=-(y/x)^(1/3)