Formula_4468

\[\left.\begin{array}{c}u\left(x_{1}, 0\right)=\varphi\left(x_{1}\right), \\\left.\frac{\partial u\left(x_{1}, x_{2}\right)}{\partial x_{2}}\right|_{x_{2}=0}=\psi\left(x_{1}\right), \quad 0 \leqslant x_{1} \leqslant l,\end{array}\right\}\]