Let A(t)=15(0.8)^0.2t (in milligrams) be the amount of drug in a patients body at time where t is the number of hours after the drug was given to the patient. Find the instantaneous rate if change of the amount of drug in the patients body 6 hours after drug was

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### Exponential and Logarithmic Calculus Problem

**Problem Statement:**

Given the function \( A(t) = 15(0.8)^{0.2t} \) (in milligrams), which represents the amount of drug in a patient's body at time \( t \), where \( t \) is the number of hours after the drug was administered:

- Find the instantaneous rate of change of the amount of drug in the patient's body 6 hours after the drug was given. 
- Provide the answer in appropriate units.

**Solution Approach:**

To find the instantaneous rate of change (which is the derivative) of the function \( A(t) \) at \( t = 6 \) hours, follow these steps:

1. **Function Given:**
   \[
   A(t) = 15(0.8)^{0.2t}
   \]

2. **Differentiate \( A(t) \):**
   - Use the chain rule and the properties of exponential functions to differentiate.

   Let’s denote \( A(t) \) in terms of a simpler variable:
   \[
   A(t) = 15 \cdot e^{0.2t \ln(0.8)}
   \]

   Now, differentiate \( A(t) \):
   \[
   \frac{dA(t)}{dt} = 15 \cdot \left(0.2 \ln(0.8) \cdot e^{0.2t \ln(0.8)}\right)
   \]

   Therefore,
   \[
   \frac{dA(t)}{dt} = 15 \cdot 0.2 \ln(0.8) \cdot (0.8)^{0.2t}
   \]

3. **Evaluate the Derivative at \( t = 6 \):**
   \[
   \frac{dA}{dt} \Bigg|_{t=6} = 15 \cdot 0.2 \ln(0.8) \cdot (0.8)^{1.2}
   \]

4. **Simplify the Expression:**
   - \( \ln(0.8) \) is a constant.
   - \( (0.8)^{1.2} \) can be calculated for the specific value.

   \(\ln(0.8) \approx
Transcribed Image Text:### Exponential and Logarithmic Calculus Problem **Problem Statement:** Given the function \( A(t) = 15(0.8)^{0.2t} \) (in milligrams), which represents the amount of drug in a patient's body at time \( t \), where \( t \) is the number of hours after the drug was administered: - Find the instantaneous rate of change of the amount of drug in the patient's body 6 hours after the drug was given. - Provide the answer in appropriate units. **Solution Approach:** To find the instantaneous rate of change (which is the derivative) of the function \( A(t) \) at \( t = 6 \) hours, follow these steps: 1. **Function Given:** \[ A(t) = 15(0.8)^{0.2t} \] 2. **Differentiate \( A(t) \):** - Use the chain rule and the properties of exponential functions to differentiate. Let’s denote \( A(t) \) in terms of a simpler variable: \[ A(t) = 15 \cdot e^{0.2t \ln(0.8)} \] Now, differentiate \( A(t) \): \[ \frac{dA(t)}{dt} = 15 \cdot \left(0.2 \ln(0.8) \cdot e^{0.2t \ln(0.8)}\right) \] Therefore, \[ \frac{dA(t)}{dt} = 15 \cdot 0.2 \ln(0.8) \cdot (0.8)^{0.2t} \] 3. **Evaluate the Derivative at \( t = 6 \):** \[ \frac{dA}{dt} \Bigg|_{t=6} = 15 \cdot 0.2 \ln(0.8) \cdot (0.8)^{1.2} \] 4. **Simplify the Expression:** - \( \ln(0.8) \) is a constant. - \( (0.8)^{1.2} \) can be calculated for the specific value. \(\ln(0.8) \approx
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