Answer
11
Work Step by Step
div $\textbf{F}=\nabla\cdot \textbf{F}=\nabla\cdot\langle x^{2}z,-2xz,yz\rangle$
$=\frac{\partial}{\partial x}(x^{2}z)+\frac{\partial}{\partial y}(-2xz)+\frac{\partial}{\partial z}(yz)$
$=2xz+0+y=2xz+y$
Knowing that $(x,y,z)=(2,-1,3)$, We get
div $\textbf{F}=2\times2\times3+(-1)=11$
