ແກ້ frac{partial^{2}u}{partialx^{2}}+partial^2u/partial^2z+partial^2u/partialy^2=0

$$\frac { \partial ^ { 2 } u } { \partial x ^ { 2 } } + \frac { \partial ^ { 2 } u } { \partial ^ { 2 } z } + \frac { \partial ^ { 2 } u } { \partial y ^ { 2 } } = 0$$

ແກ້ສຳລັບ x (complex solution)

$$x\in \mathrm{C}$$

$$u=0\text{ and }z\neq 0\text{ and }∂\neq 0$$

ແກ້ສຳລັບ u

$$u=0$$

$$∂\neq 0\text{ and }z\neq 0$$

ແກ້ສຳລັບ x

$$x\in \mathrm{R}$$

$$u=0\text{ and }z\neq 0\text{ and }∂\neq 0$$