Chapter 3: Problem 41
Solve the given problems. A truck travels \(300 \mathrm{km}\) in \(t-3 \mathrm{h}\). Express the average speed \(s\) of the truck as a function of \(t .\) What are the domain and range of \(s=f(t) ?\)
Short Answer
Expert verified
The function is \(s(t) = \frac{300}{t-3}\). Domain: \(t \in \mathbb{R}, t \neq 3\). Range: \(s \in \mathbb{R}, s \neq 0\).
Step by step solution
01
Understand the Problem
We need to express the average speed of a truck as a function of time and find the domain and range of this function. The truck travels 300 km in a time duration of \(t-3\) hours.
02
Write the Formula for Average Speed
The formula for average speed \(s\) is given by \(s = \frac{\text{Total Distance}}{\text{Total Time}}\). In this case, the total distance is 300 km, and the total time is \(t-3\) hours.
03
Express Speed as a Function
Substitute the values into the formula: \[ s = \frac{300}{t-3} \] This equation expresses the average speed as a function of \(t\), denoted as \(s = f(t)\).
04
Determine the Domain of the Function
The domain of a function is the set of all possible input values (in this case, \(t\)) that the function can accept. Since division by zero is undefined, \(t-3\) cannot be zero. Therefore, \(t eq 3\). The domain is all real numbers except 3: \(t \in \mathbb{R}, t eq 3\).
05
Determine the Range of the Function
The range is all possible output values of the function. Since \(s = \frac{300}{t-3}\), \(s\) can take any non-zero real number value (positive if \(t > 3\), negative if \(t < 3\)). Thus, the range is all real numbers excluding zero: \(s \in \mathbb{R}, s eq 0\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Domain and Range
In mathematics, the domain and range of a function are essential concepts that describe where a function can take, or output, its values. The domain is the complete set of possible values of the independent variable, which is often represented by the letter \( t \) in this context. For our problem, we are asked to find the domain of the function \( s = f(t) = \frac{300}{t-3} \).
Let's break it down:
Let's break it down:
- The denominator \( t-3 \) cannot equal zero, as division by zero is undefined. Therefore, \( t eq 3 \).
- Thus, the domain is all real numbers except when \( t = 3 \). We express this as \( t \in \mathbb{R}, t eq 3 \).
- If \( t > 3 \), \( s \) is positive.
- If \( t < 3 \), \( s \) is negative.
Function of Time
Expressing speed as a function of time is crucial in understanding how speed changes based on the time variable. In our problem, the truck's average speed is given as a function of time, \( s = f(t) \), where:\[s = \frac{300}{t-3}\]This equation indicates that:
- The speed \( s \) depends on the time \( t \) measured from 3 hours earlier.
- Speed increases as the denominator \( t-3 \) increases, meaning time passes beyond 3 hours.
Rational Functions
A rational function is a type of function that can be expressed as the quotient of two polynomials. Our problem's average speed function \( s = \frac{300}{t-3} \) is a classic example of a rational function:
- The numerator is the constant polynomial \( 300 \).
- The denominator is a linear polynomial \( t-3 \).
- They are undefined wherever the denominator equals zero. For our function, this happens at \( t = 3 \).
- They can create vertical asymptotes at these points, where the function values can become unbounded. This unbounded behavior is a critical point in understanding the nature of rational functions.
- The graphs of rational functions can also exhibit horizontal asymptotes, indicating end behavior where the function approaches a line but never actually meets it.