███████ ███ ██████

█████████████ █

██ ████████ ██ █████ ███ ████████ ${\displaystyle \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ ███'███████ ██ ██ ██████ ${\displaystyle \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ ██████████ █████ ██████████ ${\displaystyle \mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$. ██ █████ ${\displaystyle {\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\frac{\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}}$ ████████ █████ ███ █'████████ ██ ██████████ ${\displaystyle \text{<span word-length="1" class="word redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ ██ ${\displaystyle \mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ ██ ██████ ${\displaystyle \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$, ██████:

${\displaystyle (\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\cdot \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>})\text{<span word-length="1" class="word redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}=\frac{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\mathrm{<span\; word-length="3"\; class="word\; redacted">███</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}\text{<span word-length="1" class="word redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$

████ ${\displaystyle \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ █ ██ ███████ ███████ ████ ██████████. ████ ███ █'████████ ██ ██████ ██████ ███████ █ ${\displaystyle \text{<span word-length="1" class="word redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ ████████ ████ █████████ ██ ${\displaystyle \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ █ ${\displaystyle \text{<span word-length="1" class="word redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}=\frac{\mathrm{<span\; word-length="3"\; class="word\; redacted">███</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}\text{<span word-length="1" class="word redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ ██ ██:

${\displaystyle (\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\cdot \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>})\text{<span word-length="1" class="word redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}={\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\text{<span word-length="1" class="word redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$

██ ██████ ███████ ██████████ ██ ██████████ ${\displaystyle \mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ █ ██████:

${\displaystyle {\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>})={\int }_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\cdot \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>})\text{<span word-length="1" class="word redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}={\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\int }_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\text{<span word-length="1" class="word redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$

██ ███ █'█████████ ████████ ████'██████ ██████ █ ████ █ ${\displaystyle \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$.

█████████████ █

███ ${\displaystyle \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}={\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\frac{\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}={\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\frac{{\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}}$ ████ ████'█████████ █████. ${\displaystyle \mathrm{\forall }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\ne \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ ████ ███:

${\displaystyle \mathrm{\nabla }\cdot \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}=\frac{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}\frac{\mathrm{\partial }({\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>})}{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}=\frac{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}\frac{\mathrm{\partial }({\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\frac{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}})}{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}=\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ (███████ █████ ██████████ ██ ██████████ ████████)

██ █████████ ██████ ██ █████████ ████████ ${\displaystyle \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\subseteq {\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}$ ██████████ ██ ███ ██████████ ██████ █ ██████ ${\displaystyle \mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ ███ ███ ████████ █'███████ (█████ ██ ███████████ ███ █████). ███████ ${\displaystyle \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\in {\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>})}$, ████ ██ ███████ █████ ██████████ █ ██████:

${\displaystyle {\oint }_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\cdot \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}={\int }_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\mathrm{\nabla }\cdot \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}=\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ ██████ ██ ██████████ █ █████ ██ █████ █

█ ██████ ██ ██████ █ █████ ███ █████████ ██████████ ██████ ███ ███ █████████ █'███████.

██████████ ███ ███ ${\displaystyle \mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ █████████ ██ ███ ███████ █'███████. ██ ███████ █████ ██████████ (█████ ████████ █████ █████) ███ █ ███████████ ██ ██████ ${\displaystyle \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\notin {\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>})}$ (███ █ ███████ ████████ ████'███████).

███ ██████ ${\displaystyle \mathrm{\partial }{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>})}$ ██ ██████████ ███ ████████ ███ █████ ██ ██████ █ ████████ ████'███████ (███ ██████ ██████████ ███████ ██████ █████████ ██ █) █ ${\displaystyle \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}=\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\setminus {\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>})}$ ██ ██████ █ █████ ██ █████. ████ ███ ███ ${\displaystyle \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\in {\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>})}$ █ ██████ ██ ██████ █████ ${\displaystyle \mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ (███ █ ███ ██████████ ██████) █ █████ ██████ █'███████ █ ███████ ████ ██████████. ███████

${\displaystyle {\oint }_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\cdot \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}=({\oint }_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\cdot \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}-{\oint }_{\mathrm{\partial }{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>})}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\cdot \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>})+{\oint }_{\mathrm{\partial }{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>})}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\cdot \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}=}$

${\displaystyle {\oint }_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\cdot \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}+{\oint }_{\mathrm{\partial }{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>})}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\cdot \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}=\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}+{\oint }_{\mathrm{\partial }{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>})}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\cdot \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}=}$

${\displaystyle {\oint }_{\mathrm{\partial }{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>})}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\frac{{\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}\cdot {\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}=\frac{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}{\oint }_{\mathrm{\partial }{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>})}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}=\frac{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}=\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}$

█████ █████████

██ █████ █████████ ███ █████ ${\displaystyle \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ ████████ ██ ███ ██████ ██████ ${\displaystyle {\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}$ █████ ███ █████ ${\displaystyle {\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}$ ████:

${\displaystyle \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}=\frac{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\frac{\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}-{\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}{{\left|\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}-{\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\right|}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}}$

██ ███████ ███ ██ ██████ ██████████ ██ █████ ${\displaystyle \mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ ██ ██ ██████ ${\displaystyle \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ █ ████ ██:

${\displaystyle {\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>})={\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}$

██████ ██ ██ ██████████ ${\displaystyle \mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ ███ ████████ ${\displaystyle {\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}$ ██ ██████ █ █████. ███ ████ ██ ███ ███████ ██████████ ███████ ████ ██████████:

${\displaystyle {\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>})=\sum _{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}$

█ ████████ ██ ████████ ██ ██:

${\displaystyle {\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>})={\int }_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\text{<span word-length="1" class="word redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$

████ ${\displaystyle \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ █ ██ ███████ █████ ███████ ██████, ████ █████ ███████ ██ ███████ ██ ██████████████. ██████ ██ ███████ █████ ██████████, ███████████ ███ ██████████ ██ ███████:

${\displaystyle \mathbf{\nabla }\cdot \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}=\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$

████ █████████ █ ██ █████ █████ █████████ ██ ███████, ██ █ ██████ █████ ███████: ██ ███████ ██ ██████ ███████ ███████ ████ ████ ████████ ███████ ███████████.

███ ████ ██ █████████ ███████, ████████ █ ████████ (████ ██ █████), ██ ████████████ █████████ ████████ ${\displaystyle {\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}$ █ ██ ██████ (█ ███ ██ ███████) █ ██ ██ ${\displaystyle \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}=\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}/{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}$. ██ ███ ██████ █████████ ██ ███████ ██ █████ ████████████ ██ █████ █████████:

${\displaystyle \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}=\frac{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}\frac{\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}-{\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}{{\left|\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}-{\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\right|}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}}$

██ ███████ ██████ ████ ██ ████████ ████████████ ███████ █ ██████:

${\displaystyle {\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>})=\frac{{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\mathbf{\nabla }\cdot \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}=\frac{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}$

████ ${\displaystyle \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}={\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}$.

█████ █████████

█ █████ ████'███████ ██ ████████ █████████, ██ ███████ ██ █████ █████████ ███'█████████ █████████ ${\displaystyle \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ ██████ █████████████ ██ █████:

${\displaystyle {\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}(\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>})={\oint }_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\cdot \text{<span word-length="1" class="word redacted">█</span>}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}=\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathbf{\nabla }\cdot \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}=\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$

███ ███████ ██ █████████████ ███ █████ █████████. ██ ███████████, ██ ███████ █████ ███ █████████ █ ██ ███████ █████████ ██ ███████.

██ █████ ██ ████-██████ ████████ ███ ██ █████ ██ █████ ███ █'█████████ █████████, ███████:

${\displaystyle \mathbf{\nabla }\cdot \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}=\mathbf{\nabla }\cdot \frac{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\oint }_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\frac{\mathbf{\text{<span word-length="1" class="word redacted">█</span>}}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}{\prime }^{}\times \mathrm{\partial }\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}{|\mathrm{\partial }\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}{|}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}=\frac{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\oint }_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\mathbf{\nabla }\cdot \left(\text{<span word-length="1" class="word redacted">█</span>}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}{\prime }^{}\times \frac{\mathrm{\partial }\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}{|\mathrm{\partial }\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}{|}^{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}}\right)=-\frac{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\oint }_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\mathbf{\nabla }\cdot \left(\text{<span word-length="1" class="word redacted">█</span>}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}{\prime }^{}\times \mathbf{\nabla }\frac{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{|\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}|}\right)}$

███████████ █'████████ ███ ████████ ██████:

${\displaystyle \mathbf{\nabla }\cdot (\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\times \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>})=\mathbf{\nabla }\times \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\cdot \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}-\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}\cdot \mathbf{\nabla }\times \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}$

██ ███████:

${\displaystyle \mathbf{\nabla }\cdot \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}=-\frac{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\oint }_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\left(\mathbf{\nabla }\times \mathbf{\text{<span word-length="1" class="word redacted">█</span>}}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}{\prime }^{}\right)\cdot \mathbf{\nabla }\frac{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{|\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}|}+\frac{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{\oint }_{\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}\mathbf{\text{<span word-length="1" class="word redacted">█</span>}}\mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}{\prime }^{}\cdot \mathbf{\nabla }\times \mathbf{\nabla }\frac{\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}{|\mathrm{\partial }\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}|}=\mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$

████ ███████████ █ █████████████ █████ ██████ █'█████████ █████ ██████ █████ ██████████ ${\displaystyle \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$, ${\displaystyle \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ █ ${\displaystyle \mathrm{<span\; word-length="1"\; class="word\; redacted">█</span>}}$, █ ███ █████ ██████████ ███████ █████ █████ ███████ ██ █████████ ██ ████████████, ██ ███████ ██ ██████ ██ ██ █████████ █ █████████████ █████, ██ ██████ █ █████ ████████████ ████ █████████████.

█ ██████ █████ █ █████████ ███████ █████ █████ █████████████ █ ██████ █████████: ██ ██ ██████████ ███ ███████ ${\displaystyle \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ █ █████████████ █████, ██ ███ █████████ █████████ ██ ██████ ████ ████'████ █████. █ ██████, ██████████ ██ ███████ █████ ██████████, ██ ██████ ██ ${\displaystyle \mathbf{<span\; word-length="1"\; class="word\; redacted">█</span>}}$ ██████████ ██ █████████ ███ ██████ ████ █████.