(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

See photo, part b and c

2. Relevant equations

3. The attempt at a solution

For part b

It seems it is trival, in part a we have proved that [itex]f_{x}[/itex] and [itex]f_{y}[/itex] exist. Obviously, they are differentiable for x and y[itex]\neq[/itex]0

For part c.

It seems there are 2 method to do it.

1. Use first principle.(i.e. take limit)

2.Find [itex]f_{xy}[/itex] and [itex]f_{yx}[/itex]

If they equal each other, then f is differentiable at(0,0)

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# Homework Help: How to prove differentiable everywhere?

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