单项选择题
A.A的任意m个列向量必线性无关. B.A的任意m阶子式不等于零. C.若矩阵B满足BA=0,则B=0. D.A通过初等行变换,必可以化为(Em,O)的形式.
A.f(-x,-y)=f(x,y). B.f(-x,-y)=-f(x,y). C.f(-x,-y)=f(x,-y)=-f(x,y). D.f(-x,-y)=f(x,-y)=f(x,y).
A.I<0. B.I=0. C.I>0. D.不能确定.