Chọn đáp án đúng?
12/20
Cho hàm số\[{\rm{z = f(x, y) = }}{{\rm{x}}^{{\rm{20}}}}{\rm{ + }}{{\rm{y}}^{{\rm{20}}}}{\rm{ + }}{{\rm{x}}^{{\rm{10}}}}{{\rm{y}}^{{\rm{11}}}}\]. Chọn đáp án đúng?
\[{\rm{z}}_{{{\rm{x}}^{\rm{3}}}{{\rm{y}}^{{\rm{19}}}}}^{{\rm{22}}}{\rm{ = z}}_{{{\rm{y}}^{\rm{3}}}{{\rm{x}}^{{\rm{19}}}}}^{{\rm{22}}}{\rm{ = 1}}\]
\[{\rm{z}}_{{{\rm{x}}^{{\rm{13}}}}{{\rm{y}}^{\rm{9}}}}^{{\rm{22}}}{\rm{ = z}}_{{{\rm{y}}^{\rm{6}}}{{\rm{x}}^{{\rm{16}}}}}^{{\rm{22}}}{\rm{ = 2}}\]
\[{\rm{z}}_{{{\rm{x}}^{\rm{7}}}{{\rm{y}}^{{\rm{15}}}}}^{{\rm{22}}}{\rm{ = z}}_{{{\rm{y}}^{\rm{6}}}{{\rm{x}}^{{\rm{16}}}}}^{{\rm{22}}}{\rm{ = 0}}\]
\[{\rm{z}}_{{{\rm{x}}^{{\rm{11}}}}{{\rm{y}}^{{\rm{11}}}}}^{{\rm{22}}}{\rm{ = z}}_{{{\rm{y}}^{{\rm{11}}}}{{\rm{x}}^{{\rm{11}}}}}^{{\rm{22}}}{\rm{ = 3}}\]
Chọn đáp án C