Detemine where the given function is increasing and where it is decreasing. s(x) = -x 2 - 14x - 40 O Decreasing on (-~. -7), increasing on (-7, ) O Increasing on (-*, *) Decreasing on (-*, -7) and (0, *), increasing on (-7, 0) Increasing on (-*, -7), decreasing on (-7, *)

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...
icon
Related questions
Topic Video
Question

PLEASE HELP ME SOLVE

### Determine Where the Given Function is Increasing and Where It is Decreasing

Given the function:

\[ s(x) = -x^2 - 14x - 40 \]

Select the correct intervals where the function is either increasing or decreasing from the following options:

1. Decreasing on \((-\infty, -7)\), increasing on \((-7, \infty)\)
2. Increasing on \((-\infty, \infty)\)
3. Decreasing on \((-\infty, -7)\) and \((0, \infty)\), increasing on \((-7, 0)\)
4. Increasing on \((-\infty, -7)\), decreasing on \((-7, \infty)\)

### Explanation
To determine the intervals of increase and decrease, find the critical points by first taking the derivative of the function \(s(x)\):

\[ s'(x) = \frac{d}{dx}(-x^2 - 14x - 40) = -2x - 14 \]

Set the derivative equal to zero to find the critical points:

\[ -2x - 14 = 0 \]
\[ -2x = 14 \]
\[ x = -7 \]

Now, test the intervals divided by the critical point \(x = -7\) to determine where the function is increasing and decreasing. The intervals to test are \((-\infty, -7)\) and \((-7, \infty)\):

- For \(x \in (-\infty, -7)\): Choose a test point like \(x = -8\).

\[ s'(-8) = -2(-8) - 14 = 16 - 14 = 2 \]
(Note: If the derivative is positive, the function is increasing.)

- For \(x \in (-7, \infty)\): Choose a test point like \(x = 0\).

\[ s'(0) = -2(0) - 14 = -14 \]
(Note: If the derivative is negative, the function is decreasing.)

Thus, \(s(x)\) is decreasing on \((-\infty, -7)\) and increasing on \((-7, \infty)\).

Based on this analysis, the correct choice is:

***Decreasing on \((-\infty, -7)\), increasing on \((-7, \infty)\
Transcribed Image Text:### Determine Where the Given Function is Increasing and Where It is Decreasing Given the function: \[ s(x) = -x^2 - 14x - 40 \] Select the correct intervals where the function is either increasing or decreasing from the following options: 1. Decreasing on \((-\infty, -7)\), increasing on \((-7, \infty)\) 2. Increasing on \((-\infty, \infty)\) 3. Decreasing on \((-\infty, -7)\) and \((0, \infty)\), increasing on \((-7, 0)\) 4. Increasing on \((-\infty, -7)\), decreasing on \((-7, \infty)\) ### Explanation To determine the intervals of increase and decrease, find the critical points by first taking the derivative of the function \(s(x)\): \[ s'(x) = \frac{d}{dx}(-x^2 - 14x - 40) = -2x - 14 \] Set the derivative equal to zero to find the critical points: \[ -2x - 14 = 0 \] \[ -2x = 14 \] \[ x = -7 \] Now, test the intervals divided by the critical point \(x = -7\) to determine where the function is increasing and decreasing. The intervals to test are \((-\infty, -7)\) and \((-7, \infty)\): - For \(x \in (-\infty, -7)\): Choose a test point like \(x = -8\). \[ s'(-8) = -2(-8) - 14 = 16 - 14 = 2 \] (Note: If the derivative is positive, the function is increasing.) - For \(x \in (-7, \infty)\): Choose a test point like \(x = 0\). \[ s'(0) = -2(0) - 14 = -14 \] (Note: If the derivative is negative, the function is decreasing.) Thus, \(s(x)\) is decreasing on \((-\infty, -7)\) and increasing on \((-7, \infty)\). Based on this analysis, the correct choice is: ***Decreasing on \((-\infty, -7)\), increasing on \((-7, \infty)\
Expert Solution
steps

Step by step

Solved in 2 steps with 2 images

Blurred answer
Knowledge Booster
Data Collection, Sampling Methods, and Bias
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, calculus and related others by exploring similar questions and additional content below.
Recommended textbooks for you
Calculus: Early Transcendentals
Calculus: Early Transcendentals
Calculus
ISBN:
9781285741550
Author:
James Stewart
Publisher:
Cengage Learning
Thomas' Calculus (14th Edition)
Thomas' Calculus (14th Edition)
Calculus
ISBN:
9780134438986
Author:
Joel R. Hass, Christopher E. Heil, Maurice D. Weir
Publisher:
PEARSON
Calculus: Early Transcendentals (3rd Edition)
Calculus: Early Transcendentals (3rd Edition)
Calculus
ISBN:
9780134763644
Author:
William L. Briggs, Lyle Cochran, Bernard Gillett, Eric Schulz
Publisher:
PEARSON
Calculus: Early Transcendentals
Calculus: Early Transcendentals
Calculus
ISBN:
9781319050740
Author:
Jon Rogawski, Colin Adams, Robert Franzosa
Publisher:
W. H. Freeman
Precalculus
Precalculus
Calculus
ISBN:
9780135189405
Author:
Michael Sullivan
Publisher:
PEARSON
Calculus: Early Transcendental Functions
Calculus: Early Transcendental Functions
Calculus
ISBN:
9781337552516
Author:
Ron Larson, Bruce H. Edwards
Publisher:
Cengage Learning