Question
Graph the function. Then identify the domain, range, and \( y \)-intercept, and state whether the function is increasing or decreasing. \( f(x)=e^{-4 x} \) Identify the function's y-intercept. Select the correct choice below and, if necessary, fill in the answer box to complete your choice. A. The function's y-intercept is \( (0,1) \). (Type an ordered pair.) B. The function has no \( y \)-intercept. The function is decreasing.
Ask by Powell Logan. in the United States
Feb 21,2025
Upstudy AI Solution
Tutor-Verified Answer
Answer
The function's \( y \)-intercept is \( (0, 1) \).
Solution
To graph the function \( f(x) = e^{-4x} \), we can use a graphing calculator or software. However, since we are not provided with a specific graphing tool, we can analyze the function's properties to determine the domain, range, and \( y \)-intercept.
1. **Domain:** The domain of a function is the set of all possible input values for which the function is defined. For the function \( f(x) = e^{-4x} \), the domain is all real numbers since the exponential function is defined for all real numbers.
2. **Range:** The range of a function is the set of all possible output values. For the function \( f(x) = e^{-4x} \), the range is all positive real numbers since the exponential function with a negative exponent is always positive.
3. **\( y \)-intercept:** The \( y \)-intercept is the point where the function crosses the \( y \)-axis, i.e., when \( x = 0 \). To find the \( y \)-intercept, we substitute \( x = 0 \) into the function:
\[ f(0) = e^{-4(0)} = e^0 = 1 \]
Therefore, the \( y \)-intercept is \( (0, 1) \).
4. **Increasing or Decreasing:** To determine if the function is increasing or decreasing, we can analyze the derivative of the function. The derivative of \( f(x) = e^{-4x} \) is:
\[ f'(x) = -4e^{-4x} \]
Since the derivative is negative for all \( x \), the function is decreasing.
Therefore, the correct choice is:
A. The function's \( y \)-intercept is \( (0, 1) \).
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Beyond the Answer
To graph the function \( f(x) = e^{-4x} \), you'll notice that it starts at 1 when \( x = 0 \) and decreases rapidly as \( x \) increases since the exponential function with a negative exponent approaches 0 but never reaches it. The domain of this function is all real numbers \( (-\infty, \infty) \), while the range is from \( (0, 1] \). The \( y \)-intercept occurs at \( (0, 1) \), making option A the correct choice. Since the function decreases as \( x \) increases (the value of \( f(x) \) goes down), we can confidently say the function is decreasing!