Chapter 2: Problem 14
The slope of \(x+(1 / x)\) is zero when \(x=\) _______ .What does the graph do at that point?
Short Answer
Expert verified
The slope is zero at \( x = 1 \) and \( x = -1 \). The graph has horizontal tangents at these points.
Step by step solution
01
Define the function
The function given is \( f(x) = x + \frac{1}{x} \). Our goal is to find where the slope of this function is zero.
02
Find the derivative
The derivative of the function \( f(x) = x + \frac{1}{x} \) is \( f'(x) = 1 - \frac{1}{x^2} \). This derivative represents the slope of the function at any point \( x \).
03
Set the derivative equal to zero
To find where the slope is zero, set the derivative equal to zero: \( 1 - \frac{1}{x^2} = 0 \).
04
Solve for \( x \)
Rearrange the equation from Step 3 to solve for \( x \): \( 1 = \frac{1}{x^2} \). Thus, \( x^2 = 1 \), which gives us \( x = 1 \) or \( x = -1 \).
05
Analyze the critical points
At \( x = 1 \) and \( x = -1 \), the slope of the function is zero, indicating that these are critical points where the graph has horizontal tangents, typically a minimum or a maximum.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Critical Points
Critical points in calculus are places on the graph of a function where certain interesting behaviors occur. These are typically points where the derivative of the function equals zero or where the derivative does not exist. For the function in question,
- The derivative was found to be zero at specific values of \( x \), namely \( x=1 \) and \( x=-1 \).
- These values are what we call critical points.
Derivative of a Function
The derivative of a function provides insight into the function's rate of change. It's essentially like taking a peek into where the function is heading—increasing or decreasing.
For any function \( f(x) \), the derivative \( f'(x) \) tells us:
For any function \( f(x) \), the derivative \( f'(x) \) tells us:
- Where the function is rising or falling, and how steep that slope is at any given point.
- The value of the derivative at a certain point is an immediate measure of the slope of the tangent to the curve at that point.
Zero Slope
A zero slope on the graph of a function indicates a flat or horizontal tangent at that point. This occurs because the derivative, which determines the slope, equals zero. In practical terms:
- Having a zero slope means the function is neither increasing nor decreasing at that particular point.
- This situation is crucial in determining the critical points, as seen when \( f'(x) = 1 - \frac{1}{x^2} = 0 \), leading to solutions \( x=1 \) and \( x=-1 \).
Function Analysis
Function analysis is about understanding the overall behavior and characteristics of a function. This includes exploring its increases, decreases, and the potential locations where it hits its highest or lowest points.
For the function \( f(x) = x + \frac{1}{x} \):
For the function \( f(x) = x + \frac{1}{x} \):
- We found critical points at \( x=1 \) and \( x=-1 \) where the slope is zero using its derivative \( f'(x) = 1 - \frac{1}{x^2} \).
- This information is then used to determine the nature of these points—are they local maxima, minima, or something else?
- Analyzing the graph of the function further can help clarify its behavior between these critical points, giving a full view of the function’s tendencies.