Let $\mathbf { r } = x \mathbf { i } + y \mathbf { j } + z \mathbf { k }$ and $r = | \mathbf { r } |$.
Find $\nabla \cdot ( \mathbf { r } )$
A) 5
B) 3
C) 1
D) 2
E) None of these

Name: Let $\mathbf { r } = x \mathbf { i } + y \mathbf { j } + z \mathbf { k }$ and $r = | \mathbf { r } |$. Find $\nabla \cdot ( \mathbf { r } )$ A) 5 B) 3 C) 1 D) 2 E) None of these
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Quizplus · Accepted Answer

We have $
abla \cdot \mathbf{r} = \frac{\partial }{\partial x} x + \frac{\partial }{\partial y} y + \frac{\partial }{\partial z} z = 1+1+1=3$.

Let r=xi+yj+zk\mathbf { r } = x \mathbf { i } + y \mathbf { j } + z \mathbf { k }r=xi+yj+zk

Let $\mathbf { r } = x \mathbf { i } + y \mathbf { j } + z \mathbf { k }$