Differentiability of multi-variable function

59 Views Asked by At

Suppose we have the following function: $$f(x,y) = \sqrt{|xy|}$$ Is this function differentiable at $(0,0)$? Are the partial derivatives continuous at $(0,0)$?

The answer says it is differentiable but the partials are not continuous at that point

1

There are 1 best solutions below

2
On

Hint for the differentiable question: If $f$ were differentiable at $(0,0),$ then as a function of $x,$ $f(x,x) = |x|$ would be differentiable at $0.$ Is this true?