Question - 2
if \(\phi (x,y)and\psi (x,y)\) are functions with continuous second derivative, then
\(\phi (x,y)+\psi (x,y)\)
can be ecpressed as an analytic funtion of \(x+iy=(i=\sqrt { -1) } \)when
- A \(\frac { \partial \phi }{ \partial x } =-\frac { \partial \psi }{ \partial x } ;\frac { \partial \phi }{ \partial y } =\frac { \partial \psi }{ \partial y } \)
- B \(\frac { \partial \phi }{ \partial y } =-\frac { \partial \psi }{ \partial x } ;\frac { \partial \phi }{ \partial x } =\frac { \partial \psi }{ \partial y } \)
- C \(\frac { { \partial }^{ 2 }\phi }{ { \partial x }^{ 2 } } +\frac { { \partial }^{ 2 }\phi }{ { \partial y }^{ 2 } } =\frac { { \partial }^{ 2 }\psi }{ { \partial w }^{ 2 } } +\frac { \partial ^{ 2 }\psi }{ { \partial y }^{ 2 } } =1\)
- D \(\frac { \partial \phi }{ \partial x } +\frac { \partial \phi }{ \partial y } =\frac { \partial \psi }{ \partial x } +\frac { \partial \psi }{ \partial y } =0\)
