Toronto Math Forum

APM346-2022S => APM346--Lectures & Home Assignments => Chapter 1 => Topic started by: Kexin Wang on January 27, 2022, 09:12:08 PM

Title: HW1 Problem 6 （41）
Post by: Kexin Wang on January 27, 2022, 09:12:08 PM

\begin{align}
&\left\{\begin{aligned}
&u_{xy}=0,\\[2pt]
&u_{xz}=0;
\end{aligned}\right.\\[2pt]
\end{align}

For this problem I'm not sure if my approach was correct.
\begin{align}
u_{x}=f(x,z)  \textrm{   from the first equation}
\end{align}
\begin{align}
&u_{x}=g(x,y)\textrm{   from the second equation}
\end{align}
\begin{align}
\textrm{Therefore we must have   }\textrm{   }u_{x} = h(x)
\end{align}
\begin{align}
&u=H(x) + m(y,z)\textrm{ } \textrm{where}\textrm{ } H'(x)=h(x)
\end{align}

Title: Re: HW1 Problem 6 （41）
Post by: Victor Ivrii on January 28, 2022, 01:41:36 AM

Yes, it is correct: $u=H(x)+m(y,z)$ where $H$ and $m$ are arbitrary functions.