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1-u-x-x-2u-x-y-3u-y-y-u-x-0-2-xu-x-x-2xu-x-y-3u-y-y-u-y-0-




Question Number 163082 by HongKing last updated on 03/Jan/22
1. u_(x x)  - 2u_(x y)  + 3u_(y y)  - u_x  = 0  2. xu_(x x)  + 2xu_(x y)  + 3u_(y y)  + u_y  = 0
$$\mathrm{1}.\:\mathrm{u}_{\boldsymbol{\mathrm{x}}\:\boldsymbol{\mathrm{x}}} \:-\:\mathrm{2u}_{\boldsymbol{\mathrm{x}}\:\boldsymbol{\mathrm{y}}} \:+\:\mathrm{3u}_{\boldsymbol{\mathrm{y}}\:\boldsymbol{\mathrm{y}}} \:-\:\mathrm{u}_{\boldsymbol{\mathrm{x}}} \:=\:\mathrm{0} \\ $$$$\mathrm{2}.\:\mathrm{xu}_{\boldsymbol{\mathrm{x}}\:\boldsymbol{\mathrm{x}}} \:+\:\mathrm{2xu}_{\boldsymbol{\mathrm{x}}\:\boldsymbol{\mathrm{y}}} \:+\:\mathrm{3u}_{\boldsymbol{\mathrm{y}}\:\boldsymbol{\mathrm{y}}} \:+\:\mathrm{u}_{\boldsymbol{\mathrm{y}}} \:=\:\mathrm{0} \\ $$
Commented by mahdipoor last updated on 03/Jan/22
what the meaning of u_x  or u_(xy)  or ...?
$${what}\:{the}\:{meaning}\:{of}\:{u}_{{x}} \:{or}\:{u}_{{xy}} \:{or}\:…? \\ $$
Commented by mr W last updated on 03/Jan/22
u_x =(∂u/∂x)  u_y =(∂u/∂y)  u_(xx) =(∂^2 u/∂x^2 )  u_(xy) =(∂^2 u/(∂x∂y))  ...
$${u}_{{x}} =\frac{\partial{u}}{\partial{x}} \\ $$$${u}_{{y}} =\frac{\partial{u}}{\partial{y}} \\ $$$${u}_{{xx}} =\frac{\partial^{\mathrm{2}} {u}}{\partial{x}^{\mathrm{2}} } \\ $$$${u}_{{xy}} =\frac{\partial^{\mathrm{2}} {u}}{\partial{x}\partial{y}} \\ $$$$… \\ $$
Commented by mahdipoor last updated on 03/Jan/22
thank ser W
$${thank}\:{ser}\:{W}\: \\ $$

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