To express the dependence of speed \( v \) on time \( t \) for the cyclist who traveled a distance of 70 km at a constant speed, we start with the formula:
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} \]
Let \( d = 70 \) km (the distance traveled) and \( t \) be the time in hours. Then, the formula for speed \( v \) as a function of time \( t \) is:
\[ v(t) = \frac{d}{t} = \frac{70}{t} \]
Now, we can find the values for \( v(5) \), \( v(7) \), and \( v(3.5) \).
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For \( t = 5 \): \[ v(5) = \frac{70}{5} = 14 \text{ km/h} \]
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For \( t = 7 \): \[ v(7) = \frac{70}{7} = 10 \text{ km/h} \]
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For \( t = 3.5 \): \[ v(3.5) = \frac{70}{3.5} = 20 \text{ km/h} \]
Thus, the speeds corresponding to the given times are:
- \( v(5) = 14 \) km/h
- \( v(7) = 10 \) km/h
- \( v(3.5) = 20 \) km/h
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