我们说一个函数是可微的，如果这些偏导数存在。

And, we say that a function is differentiable if these things exist.

youdao

多元函数的连续性，偏导数，方向导数及可微性之间的关系。

The Relation between the Continuity, the Partial Derivatives, the Directional Derivatives and the Differentiability of a Function.

youdao

探讨二元函数的连续性、偏导数、方向导数以及可微性之间的关系，有助于我们对二元函数的学习。

A discussion of the relations between continuity, partial derivative, directional derivative and differentiability of binary function is helpful for us to study binary function.

youdao