Question

Let f(x, y)= Cos x Cos y. Then value of second order partial derivative fxy at (0,0)
0 1
О 0
O-1
O None​

Answer 1

Answer:

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Answer 2

Answer:

$f_{xy}$ at (0,0) = 0

Step-by-step explanation:

let f(x,y)=z.Then,

$f_{xy}$=$\frac{d\frac{(dz)}{dy} }{dx}$

∴$f_{xy}$=$\frac{d(\frac{cosxcosy}{dy} )}{dx}$

∴$f_{xy}$=$\frac{d(-cosxsiny)}{dx}$

∴$f_{xy}$=+sinxsiny

As sin(0)=0.

Hence,putting (0,0) in $f_{xy}$ we get  the second order partial derivative $f_{xy}$=0.