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If y=xcosu Find the value of x2uxx+2xy uxy + y2uyy
1 Answer
| written 4.6 years ago by |
Answer: By Euler's deduction, we have
$x^2 u_{xx} +2xy u_{xy}+y^2u{yy}=g(u)[g'(u)-1],$
where,$g(u)=n {f(u) \over f'(u)}.$
Here, $y=xcosu \Rightarrow {y \over x}=cosu \Rightarrow u=cos^{-1}(y/x) \Rightarrow n=1-1=0.$
Hence from the above Euler's deduction, we have $x^2 u_{xx} +2xy u_{xy}+y^2u{yy}=0.$ Answer.