$\"\"$

The function is $\"\"$ and the point is $\"\"$ .

Apply partial derivative on each side with respect to x.

$\"\"$

Substitute the point $\"\"$ in above function. $\"\"$

$\"\"$

The function is $\"\"$ .

Apply partial derivative on each side with respect to y.

$\"\"$

Substitute the point $\"\"$ in above function. $\"\"$

$\"\"$