Find fx (x,y) and fy(x,y). Then find fx (2, – 1) and fy(- 2, - 2). f(x,y) = - 7 e 8x– 5y

Calculus: Early Transcendentals
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Author:James Stewart
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Chapter1: Functions And Models
Section: Chapter Questions
Problem 1RCC: (a) What is a function? What are its domain and range? (b) What is the graph of a function? (c) How...
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Homework: HW 17.2

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Type an exact answer when finding the answer for fx(2,-1) and fy(-2,-2)

### Finding Partial Derivatives and Evaluating at Specific Points

Given the function:
\[ f(x,y) = -7 e^{8x - 5y} \]

1. **Find \( f_x(x,y) \) and \( f_y(x,y) \)**:
    - \( f_x(x,y) \) is the partial derivative of \( f \) with respect to \( x \).
    - \( f_y(x,y) \) is the partial derivative of \( f \) with respect to \( y \).

2. **Evaluate \( f_x \) and \( f_y \) at specific points**:
    - Find \( f_x(2, -1) \).
    - Find \( f_y(-2, -2) \).

#### Steps for Finding Partial Derivatives

1. **Partial Derivative with respect to \( x \) (\( f_x \))**:
   \[ f_x(x, y) = \frac{\partial}{\partial x} \left( -7 e^{8x - 5y} \right) \]

   Using the chain rule:
   \[ f_x(x, y) = -7 \cdot e^{8x - 5y} \cdot (8) \]
   \[ f_x(x, y) = -56 e^{8x - 5y} \]

2. **Partial Derivative with respect to \( y \) (\( f_y \))**:
   \[ f_y(x, y) = \frac{\partial}{\partial y} \left( -7 e^{8x - 5y} \right) \]

   Using the chain rule:
   \[ f_y(x, y) = -7 \cdot e^{8x - 5y} \cdot (-5) \]
   \[ f_y(x, y) = 35 e^{8x - 5y} \]

#### Evaluating at Specific Points

1. **Evaluate \( f_x(2, -1) \)**:
   \[ f_x(2, -1) = -56 e^{8(2) - 5(-1)} = -56 e^{16 + 5} = -56 e^{21} \]

2. **Evaluate \( f_y(-2, -2) \)**:
   \[ f_y(-2, -2)
Transcribed Image Text:### Finding Partial Derivatives and Evaluating at Specific Points Given the function: \[ f(x,y) = -7 e^{8x - 5y} \] 1. **Find \( f_x(x,y) \) and \( f_y(x,y) \)**: - \( f_x(x,y) \) is the partial derivative of \( f \) with respect to \( x \). - \( f_y(x,y) \) is the partial derivative of \( f \) with respect to \( y \). 2. **Evaluate \( f_x \) and \( f_y \) at specific points**: - Find \( f_x(2, -1) \). - Find \( f_y(-2, -2) \). #### Steps for Finding Partial Derivatives 1. **Partial Derivative with respect to \( x \) (\( f_x \))**: \[ f_x(x, y) = \frac{\partial}{\partial x} \left( -7 e^{8x - 5y} \right) \] Using the chain rule: \[ f_x(x, y) = -7 \cdot e^{8x - 5y} \cdot (8) \] \[ f_x(x, y) = -56 e^{8x - 5y} \] 2. **Partial Derivative with respect to \( y \) (\( f_y \))**: \[ f_y(x, y) = \frac{\partial}{\partial y} \left( -7 e^{8x - 5y} \right) \] Using the chain rule: \[ f_y(x, y) = -7 \cdot e^{8x - 5y} \cdot (-5) \] \[ f_y(x, y) = 35 e^{8x - 5y} \] #### Evaluating at Specific Points 1. **Evaluate \( f_x(2, -1) \)**: \[ f_x(2, -1) = -56 e^{8(2) - 5(-1)} = -56 e^{16 + 5} = -56 e^{21} \] 2. **Evaluate \( f_y(-2, -2) \)**: \[ f_y(-2, -2)
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