The flight path of a rocket, launched from the ground, is modeled by y = 0.25(40x-x²), where y is the height of the rocket in feet from the ground and x is the time in seconds after it was launched. Find the vertex of the parabola and explain what it represents in terms of the context. O (40, 0); rocket lands at 0 feet after 40 seconds O (20, 100); rocket reaches maximum height of 20 feet after 100 seconds O (40, 0); rocket reaches 40 feet after 0 seconds O (20, 100); rocket reaches maximum height 100 feet after 20 seconds

Calculus: Early Transcendentals
8th Edition
ISBN:9781285741550
Author:James Stewart
Publisher:James Stewart
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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**Understanding the Rocket's Flight Path**

The flight path of a rocket, launched from the ground, is modeled by the equation:

\[ y = 0.25(40x - x^2) \]

In this equation:
- \( y \) represents the height of the rocket (in feet) from the ground.
- \( x \) represents the time (in seconds) after the rocket has been launched.

**Question:**
Find the vertex of the parabola represented by the equation and explain what it represents in terms of the rocket's flight.

**Answer Choices:**

1. **(40, 0); rocket lands at 0 feet after 40 seconds**
2. **(20, 100); rocket reaches maximum height of 20 feet after 100 seconds**
3. **(40, 0); rocket reaches 40 feet after 0 seconds**
4. **(20, 100); rocket reaches maximum height of 100 feet after 20 seconds**

**Explanation:**

- To find the vertex of the parabola, consider the given quadratic equation \( y = 0.25 (40x - x^2) \). 
- The standard form for a quadratic equation is \( y = ax^2 + bx + c \). Here, it's helpful to rewrite the given equation into that standard form:
  \[ y = 0.25(-x^2 + 40x) \]
- The vertex form of a parabola is given by \( x = -\frac{b}{2a} \), where \( a \) and \( b \) are coefficients from the standard form equation \( ax^2 + bx + c \).
- In this case, \( a = -0.25 \) and \( b = 10 \).
- Calculate the vertex:

\[ x = -\frac{b}{2a} = -\frac{40}{2(-1)} = 20 \]

- Substituting \( x = 20 \) back into the equation to find the maximum height \( y \):

\[ y = 0.25 (40 \times 20 - 20^2) \]
\[ y = 0.25 (800 - 400) \]
\[ y = 0.25 \times 400 \]
\[ y = 100 \]

Therefore, the vertex of the parabola is at \( (20, 100) \), meaning
Transcribed Image Text:**Understanding the Rocket's Flight Path** The flight path of a rocket, launched from the ground, is modeled by the equation: \[ y = 0.25(40x - x^2) \] In this equation: - \( y \) represents the height of the rocket (in feet) from the ground. - \( x \) represents the time (in seconds) after the rocket has been launched. **Question:** Find the vertex of the parabola represented by the equation and explain what it represents in terms of the rocket's flight. **Answer Choices:** 1. **(40, 0); rocket lands at 0 feet after 40 seconds** 2. **(20, 100); rocket reaches maximum height of 20 feet after 100 seconds** 3. **(40, 0); rocket reaches 40 feet after 0 seconds** 4. **(20, 100); rocket reaches maximum height of 100 feet after 20 seconds** **Explanation:** - To find the vertex of the parabola, consider the given quadratic equation \( y = 0.25 (40x - x^2) \). - The standard form for a quadratic equation is \( y = ax^2 + bx + c \). Here, it's helpful to rewrite the given equation into that standard form: \[ y = 0.25(-x^2 + 40x) \] - The vertex form of a parabola is given by \( x = -\frac{b}{2a} \), where \( a \) and \( b \) are coefficients from the standard form equation \( ax^2 + bx + c \). - In this case, \( a = -0.25 \) and \( b = 10 \). - Calculate the vertex: \[ x = -\frac{b}{2a} = -\frac{40}{2(-1)} = 20 \] - Substituting \( x = 20 \) back into the equation to find the maximum height \( y \): \[ y = 0.25 (40 \times 20 - 20^2) \] \[ y = 0.25 (800 - 400) \] \[ y = 0.25 \times 400 \] \[ y = 100 \] Therefore, the vertex of the parabola is at \( (20, 100) \), meaning
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