Math Problem Statement

Find the maximum and minimum values of the function and the values of x and y where they occur.

F=5x+36y, subject to 7x+5y<=41, 5x+7y<=35, x>=0, y>=0.

What is the maximum value of the function?

Solution

To find the maximum and minimum values of the function F=5x+36yF = 5x + 36y subject to the given constraints, we can follow these steps:

1. Identify the constraints

The problem gives the following constraints: 7x+5y417x + 5y \leq 41 5x+7y355x + 7y \leq 35 x0x \geq 0 y0y \geq 0

2. Graph the constraints

These constraints can be represented as lines in the xyxy-plane. The feasible region is the area where all these inequalities overlap.

3. Find the corner points of the feasible region

The maximum or minimum value of a linear function subject to linear constraints occurs at one of the corner points (vertices) of the feasible region.

The corner points can be found by solving the system of equations formed by the intersection of the constraint lines.

Intersection of 7x+5y=417x + 5y = 41 and 5x+7y=355x + 7y = 35:

  1. Solve for xx and yy by solving the system: 7x+5y=417x + 5y = 41 5x+7y=355x + 7y = 35

  2. Substitute yy from one equation into the other to find xx, and then solve for yy.

Intersection of 7x+5y=417x + 5y = 41 with the axes:

For y=0y = 0: 7x=41x=4175.867x = 41 \quad \Rightarrow \quad x = \frac{41}{7} \approx 5.86

For x=0x = 0: 5y=41y=4158.25y = 41 \quad \Rightarrow \quad y = \frac{41}{5} \approx 8.2

Intersection of 5x+7y=355x + 7y = 35 with the axes:

For y=0y = 0: 5x=35x=75x = 35 \quad \Rightarrow \quad x = 7

For x=0x = 0: 7y=35y=57y = 35 \quad \Rightarrow \quad y = 5

4. Evaluate the objective function F(x,y)=5x+36yF(x, y) = 5x + 36y at each corner point

Next, evaluate F(x,y)=5x+36yF(x, y) = 5x + 36y at the vertices of the feasible region.

5. Determine the maximum and minimum values

Let's calculate these:

  • At (0,5)(0, 5):
    F(0,5)=5(0)+36(5)=180F(0, 5) = 5(0) + 36(5) = 180

  • At (7,0)(7, 0):
    F(7,0)=5(7)+36(0)=35F(7, 0) = 5(7) + 36(0) = 35

  • At (417,0)(5.86,0)( \frac{41}{7}, 0) \approx (5.86, 0):
    F(5.86,0)5(5.86)+36(0)=29.3F(5.86, 0) \approx 5(5.86) + 36(0) = 29.3

  • At (0,415)(0,8.2)(0, \frac{41}{5}) \approx (0, 8.2):
    F(0,8.2)5(0)+36(8.2)=295.2F(0, 8.2) \approx 5(0) + 36(8.2) = 295.2

  • At the intersection of 7x+5y=417x + 5y = 41 and 5x+7y=355x + 7y = 35:
    Solving the system gives us x=3x = 3 and y=4y = 4: F(3,4)=5(3)+36(4)=15+144=159F(3, 4) = 5(3) + 36(4) = 15 + 144 = 159

Conclusion:

The maximum value of F(x,y)=295.2F(x, y) = 295.2 occurs at (0,8.2)(0, 8.2). The minimum value within the feasible region is 29.329.3, which occurs at (5.86,0)(5.86, 0).

Would you like further details or any other questions on this? Here are some related questions:

  1. How do we solve the intersection of linear equations graphically?
  2. Why does the maximum or minimum value of a linear function occur at a vertex of the feasible region?
  3. How can the Simplex Method be used to solve linear programming problems?
  4. What are some real-life applications of linear programming?
  5. How can constraints change the shape and position of the feasible region?

Tip: When solving linear programming problems, ensure to evaluate the function at every vertex of the feasible region to find the maximum and minimum values.

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Math Problem Analysis

Mathematical Concepts

Linear Programming
Optimization
Inequalities
Feasible Region

Formulas

Objective function F(x, y) = 5x + 36y
Constraints: 7x + 5y <= 41, 5x + 7y <= 35, x >= 0, y >= 0

Theorems

Fundamental Theorem of Linear Programming

Suitable Grade Level

Grades 10-12