Let .
A) Do and exist? If so, find them.
B) Use the definition of directional derivative to compute for .
C) Examine whether holds, and conclude the differentiability of at the origin.

Question

Let  . 
A) Do and exist? If so, find them. 
B) Use the definition of directional derivative to compute for . 
C) Examine whether holds, and conclude the differentiability of at the origin.

Quizplus · Accepted Answer

The Answer of Let  . 
A) Do and exist? If so, find them. 
B) Use the definition of directional derivative to compute for . 
C) Examine whether holds, and conclude the differentiability of at the origin.