Formula_24234

\[\begin{gathered}\operatorname{grad}(\varphi+\psi)=\operatorname{grad} \varphi+\operatorname{grad} \psi \\\operatorname{grad}(\varphi \psi)=\varphi \operatorname{grad} \psi+\psi \operatorname{grad} \varphi \\\operatorname{grad} f(\varphi)=f^{\prime}(\varphi) \operatorname{grad} \varphi\end{gathered}\]