1. **Problem statement:**
Find an expression in $x$ for $T$, the total time in hours, that it will take Jacob to kayak from $S$ to $B$ and then run from $B$ to $F$.
2. **Given:**
- $|AB| = x$ km, where $0 \leq x \leq 8$.
- Jacob kayaks from $S$ to $B$.
- Jacob runs from $B$ to $F$.
3. **Step 1: Express distances**
- The distance from $S$ to $B$ is the straight line distance. Since $S$ is 2 km from $A$ perpendicular to $AF$, the distance $SB = \sqrt{x^2 + 2^2} = \sqrt{x^2 + 4}$ km.
- The distance from $B$ to $F$ is along $AF$, so $BF = 8 - x$ km.
4. **Step 2: Use speeds to find time**
- Let the kayaking speed be 6 km/h.
- Let the running speed be 12 km/h.
5. **Step 3: Write the total time $T$**
$$
T = \text{time kayaking} + \text{time running} = \frac{\sqrt{x^2 + 4}}{6} + \frac{8 - x}{12}
$$
6. **Final expression:**
$$
T(x) = \frac{\sqrt{x^2 + 4}}{6} + \frac{8 - x}{12}
$$
This expression gives the total time in hours for Jacob to kayak from $S$ to $B$ and then run from $B$ to $F$ as a function of $x$.
Time Expression 5Ee53E
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