Chapter 15 - Vector Analysis - 15.1 Exercises - Page 1050: 61

4

div $\textbf{F}=\nabla\cdot \textbf{F}=\nabla\cdot\langle xyz,xy,z\rangle$ $=\frac{\partial}{\partial x}(xyz)+\frac{\partial}{\partial y}(xy)+\frac{\partial}{\partial z}(z)$ $=yz+x+1$ Knowing that $(x,y,z)=(2,1,1)$, We get div $\textbf{F}=1\times1+2+1=4$