Toronto Math Forum
MAT2442018F => MAT244Lectures & Home Assignments => Topic started by: Zhiya Lou on September 16, 2018, 08:36:44 PM

HI, I don't understand the notation from these question (sec1.3); And also about its linear/nonlinear property... Thanks
22) $𝑢_{𝑥𝑥}+u_{𝑦𝑦}+𝑢𝑢_𝑥+𝑢𝑢_𝑦+u=0$
(why is it non linear?)
23) $u_{𝑥𝑥𝑥𝑥}+2u_{𝑥𝑥𝑦𝑦}+𝑢_{𝑦𝑦𝑦𝑦}=0$

$u_x$ = partial derivative of $u$ with respect to $x$
$u_{xx}$ = second partial derivative of $u$ with respect to $x$
22) is not linear because of the two terms where u is multiplied by $u_x$ and $u_y$
I fixed math expressions for both of you. "Edit" to see how it should be doneV.I.