Chapter 1: Problem 25
Use your grapher to find the breakeven quantities for the given profit functions and the value of \(x\) that maximizes the profit. $$ P(x)=-4 x^{2}+38.4 x-59.36 $$
Short Answer
Expert verified
Breakeven at \( x \approx 1.94 \) and \( x \approx 7.66 \). Max profit at \( x = 4.8 \).
Step by step solution
01
Understand the Problem
We need to find the breakeven quantities and the value of \( x \) that maximizes the profit from the given profit function \( P(x) = -4x^2 + 38.4x - 59.36 \). The breakeven quantities are the values of \( x \) where profit \( P(x) = 0 \). The maximum profit occurs at the vertex of the parabola since this is a quadratic function.
02
Breakeven Analysis
To find the breakeven points, we need to set the profit equation equal to zero and solve for \( x \):\[ -4x^2 + 38.4x - 59.36 = 0 \]Use the quadratic formula \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \) where \( a = -4 \), \( b = 38.4 \), and \( c = -59.36 \).
03
Solve Using the Quadratic Formula
First, calculate the discriminant:\[ b^2 - 4ac = (38.4)^2 - 4(-4)(-59.36) \]\[ = 1474.56 - 949.76 = 524.8 \]Now, use the quadratic formula:\[ x = \frac{-38.4 \pm \sqrt{524.8}}{-8} \]
04
Calculate Roots
First, find the square root of the discriminant:\[ \sqrt{524.8} \approx 22.9 \]Substitute back into the quadratic formula for each root:\[ x_1 = \frac{-38.4 + 22.9}{-8} = 1.9375 \]\[ x_2 = \frac{-38.4 - 22.9}{-8} = 7.6625 \]These are the breakeven quantities.
05
Find Maximum Profit
The maximum profit occurs at the vertex of the parabola. The \( x \)-coordinate of the vertex is found by:\[ x_{vertex} = \frac{-b}{2a} = \frac{-38.4}{2(-4)} = \frac{38.4}{8} = 4.8 \]
06
Conclusion
The breakeven quantities are approximately \( x = 1.94 \) and \( x = 7.66 \). The value of \( x \) that maximizes the profit is \( 4.8 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Breakeven Analysis
Breakeven analysis helps businesses determine when they will start to make a profit. In simple terms, it is the point where costs equal revenues, resulting in zero profit or loss. For our quadratic function \( P(x) = -4x^2 + 38.4x - 59.36 \), the goal is to find the values of \( x \) where \( P(x) = 0 \). These are known as the breakeven points.
- Set the profit function equal to zero: \(-4x^2 + 38.4x - 59.36 = 0\).
- Solve this equation to find the breakeven quantities.
Profit Maximization
Profit maximization entails identifying the level of sales that yields the highest possible profit. For quadratic profit functions like \(P(x) = -4x^2 + 38.4x - 59.36\), profit is maximized at the vertex of the parabola. Why? The nature of a downward-opening parabola means it reaches its peak at the top, which represents maximum profit.
- Calculate the vertex using \(x = \frac{-b}{2a}\).
- This \(x\) value provides the quantity at which maximum profit is achieved.
Quadratic Formula
The quadratic formula is a powerful tool used to solve quadratic equations of the form \(ax^2 + bx + c = 0\). It is given by:\[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]This formula helps find the roots of the quadratic equation, which are crucial in breakeven analysis and profit maximization.
- Calculate the discriminant, \(b^2 - 4ac\), to determine the nature of the roots (real or complex).
- Use the formula to solve for \(x\), providing essential values like breakeven points in this context.
Vertex of a Parabola
A parabola's vertex represents either the highest or lowest point of the curve. For a downward-facing parabola, it is the top point, symbolizing maximum value, such as profit.
- The vertex can be calculated using \(x = \frac{-b}{2a}\) from the quadratic equation \(ax^2 + bx + c\).
- It gives insight into optimal points for functions like cost, revenue, or profit.