To maximize the objective function \( P = 3x + 2y \) subject to the constraints:
- \( x + y \leq 6 \)
- \( 2x + y \leq 8 \)
- \( x \geq 0 \)
- \( y \geq 0 \)
we will follow these steps:
Step 1: Graph the Constraints
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Graph \( x + y \leq 6 \):
- The line \( x + y = 6 \) has intercepts at \( (6, 0) \) and \( (0, 6) \).
- Below this line represents the region for the inequality.
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Graph \( 2x + y \leq 8 \):
- The line \( 2x + y = 8 \) intersects the axes at \( (4, 0) \) and \( (0, 8) \).
- The region below this line represents the inequality.
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Non-negativity Constraints:
- \( x \geq 0 \) means we are only considering the right half of the plane.
- \( y \geq 0 \) means we are only considering the top half of the plane.
Step 2: Find the Feasible Region
To find the feasible region, we will graph the lines and see where they intersect:
- The intersection of \( x + y = 6 \) and \( 2x + y = 8 \): \[ \begin{align*} x + y &= 6 \quad \text{(1)} \ 2x + y &= 8 \quad \text{(2)} \end{align*} \] Subtracting (1) from (2): \[ 2x + y - (x + y) = 8 - 6 \ x = 2 \] Substitute \( x = 2 \) into equation (1): \[ 2 + y = 6 \implies y = 4 \] So, the intersection point is \( (2, 4) \).
Next, we find the vertices of the feasible region, which are determined by the intersection points and the axes:
- The line \( x + y = 6 \) intersects the axes at \( (6, 0) \) and \( (0, 6) \).
- The line \( 2x + y = 8 \) intersects the axes at \( (4, 0) \) and \( (0, 8) \).
The intersecting points inside the non-negative quadrant that satisfy both inequalities are:
- \( (0, 0) \) (origin)
- \( (0, 6) \) (from \( x+y=6 \))
- \( (4, 0) \) (from \( 2x+y=8 \))
- \( (2, 4) \) (intersection point)
Step 3: Evaluate the Objective Function at Each Vertex
Now we evaluate \( P = 3x + 2y \) at the vertices of the feasible region:
- At \( (0, 0) \): \[ P = 3(0) + 2(0) = 0 \]
- At \( (0, 6) \): \[ P = 3(0) + 2(6) = 12 \]
- At \( (4, 0) \): \[ P = 3(4) + 2(0) = 12 \]
- At \( (2, 4) \): \[ P = 3(2) + 2(4) = 6 + 8 = 14 \]
Step 4: Find the Maximum Value
From our evaluations, we have:
- \( P(0, 0) = 0 \)
- \( P(0, 6) = 12 \)
- \( P(4, 0) = 12 \)
- \( P(2, 4) = 14 \)
The maximum value is \( 14 \), which occurs at the point \( (2, 4) \).
Conclusion
The values of \( x \) and \( y \) that maximize \( P \) are \( \boxed{(2, 4)} \).