Theorem 1 if is differentiable at, and is a local extreme value of, then.

定理1设函数在处可导，且在处取得极值，那么。

youdao

Theorem 1 if is differentiable at, and is a local extreme value of, then.

定理1设函数在处可导，且在处取得极值，那么。

youdao