/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 19 Find the value of \(x\) that max... [FREE SOLUTION] | 91Ó°ÊÓ

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Find the value of \(x\) that maximizes the profit. Find the break-even quantities (if they exist); that is, find the value of \(x\) for which the profit is zero. Graph the solution. $$ R(x)=-2 x^{2}+30 x, C(x)=10 x+42 $$

Short Answer

Expert verified
Maximum profit occurs at \( x = 5 \); break-even points are around \( x = 2 \) and \( x = 10.5 \).

Step by step solution

01

Understand the Problem

The revenue function is given by \( R(x) = -2x^2 + 30x \) and the cost function is \( C(x) = 10x + 42 \). We need to find the value of \( x \) that maximizes the profit and the values of \( x \) where profit is zero. Remember, profit \( P(x) \) is calculated as \( P(x) = R(x) - C(x) \).
02

Define the Profit Function

Subtract the cost function from the revenue function to find the profit function: \( P(x) = R(x) - C(x) = (-2x^2 + 30x) - (10x + 42) \). Simplify to get \( P(x) = -2x^2 + 20x - 42 \).
03

Find the Maximum Profit

The profit function is a quadratic function \( P(x) = -2x^2 + 20x - 42 \). To find the maximum profit, use the vertex formula \( x = -\frac{b}{2a} \), where \( a = -2 \) and \( b = 20 \). Compute \( x = -\frac{20}{2(-2)} = 5 \). So, \( x = 5 \) maximizes the profit.
04

Verify the Maximum Profit Value

Substitute \( x = 5 \) into the profit function to verify: \( P(5) = -2(5)^2 + 20(5) - 42 = -50 + 100 - 42 = 8 \). The maximum profit is 8 when \( x = 5 \).
05

Find the Break-Even Quantities

Set \( P(x) = -2x^2 + 20x - 42 = 0 \) and solve for \( x \). Use the quadratic formula: \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \), with \( a = -2 \), \( b = 20 \), \( c = -42 \). Calculate the discriminant: \( b^2 - 4ac = 400 + 336 = 736 \). Compute \( x = \frac{-20 \pm \sqrt{736}}{-4} \), giving \( x \approx 2 \) and \( x \approx 10.5 \). These are the break-even points.
06

Graph the Solution

Plot the function \( P(x) = -2x^2 + 20x - 42 \) on a graph. Highlight the maximum point at \( x = 5 \), and mark the break-even points around \( x = 2 \) and \( x = 10.5 \). The parabola opens downward, confirming that \( x = 5 \) is the maximum.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Quadratic Functions
Quadratic functions are fundamentally important in mathematics, especially when dealing with scenarios like profit maximization. They are expressed in the standard form as \( ax^2 + bx + c \). Here, the function exhibits a symmetric U-shaped curve known as a parabola when graphed. A vital aspect of quadratic functions is their ability to model real-world problems where relationships are not linear. In our exercise, the profit function \( P(x) = -2x^2 + 20x - 42 \) is quadratic. The coefficient \( a = -2 \) indicates that the parabola opens downward, which is typical for maximization problems. Understanding the nature of quadratic functions is key because it allows us to determine whether the parabola opens upward or downward and locate its maximum or minimum point, as these tell us whether we are maximizing or minimizing a problem. For profit functions, this is particularly helpful as businesses often seek to find the maximum profit point.
Break-Even Analysis
Break-even analysis is an essential financial assessment tool that helps businesses understand the level at which neither profit nor loss is made. It uses the concept of setting the profit function to zero and solving the resultant equation. The break-even points occur where the revenue equals the costs, meaning \( P(x) = 0 \). In our solution, the profit function \(-2x^2 + 20x - 42 = 0\) was set up to find these critical points. Utilizing the quadratic formula, \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \), the break-even quantities were determined to be approximately \( x = 2 \) and \( x = 10.5 \). These values indicate the quantity of products sold where revenues equate to costs, and no profit is made. Break-even analysis is crucial to make informed decisions related to pricing and cost management.
Vertex Formula
The vertex formula is instrumental in quadratic functions, particularly when locating the maximum or minimum point on a parabola, which is called the vertex. For quadratic functions in standard form \( ax^2 + bx + c \), the vertex's horizontal coordinate can be found using \( x = -\frac{b}{2a} \). This tells us where the maximum or minimum value of the function occurs.In the context of our exercise, we used the vertex formula to find the maximum profit point. With the profit function \( P(x) = -2x^2 + 20x - 42 \), substituting \( a = -2 \) and \( b = 20 \) into the vertex formula gave us \( x = 5 \). This calculation reveals that the maximum profit occurs when 5 units are produced and sold. Calculating this maximum point efficiently enables businesses to adjust their production levels to optimize profitability, making the vertex formula a powerful tool in economic and business calculations.

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