Question
Let $\mathbf{r}(t)=\ln t \mathbf{i}+2 t \mathbf{j}+t^{2} \mathbf{k} .$ Find$$\begin{array}{llll}{\text { (a) }\left\|\mathbf{r}^{\prime}(t)\right\|} & {\text { (b) } \frac{d s}{d t}} & {\text { (c) } \int_{1}^{3}\left\|\mathbf{r}^{\prime}(t)\right\| d t} & {}\end{array}$$
Step 1
The derivative of a vector function is found by taking the derivative of each of its components. So, we have: $$ \mathbf{r}^{\prime}(t)=\frac{d}{dt}(\ln t \mathbf{i}+2 t \mathbf{j}+t^{2} \mathbf{k})=\frac{1}{t} \mathbf{i}+2 \mathbf{j}+2t \mathbf{k} $$ Show more…
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