Let \(f\) and \(g\) denote smooth functions. Then
\[ \Delta(fg) = (\Delta f)\, g + 2 \nabla f \cdot \nabla g + f\, \Delta g. \]Let \(f\) and \(g\) denote smooth functions. Then
\[ \Delta(fg) = (\Delta f)\, g + 2 \nabla f \cdot \nabla g + f\, \Delta g. \]