A.一定是函數(shù)的可微點(diǎn) B.一定是函數(shù)的不可微點(diǎn) C.一定是函數(shù)的駐點(diǎn) D.或是駐點(diǎn)或是不可微點(diǎn)
A.各個(gè)偏導(dǎo)數(shù)大于0 B.各個(gè)偏導(dǎo)數(shù)小于0 C.各個(gè)偏導(dǎo)數(shù)等于0 D.各二階偏導(dǎo)數(shù)等于0