Chapter 2: Problem 56
If you zoom in (with your calculator) on the graph of \(y=f(x)\) in a small interval around \(x=10\) and see a straight line, then the slope of that line equals the derivative \(f^{\prime}(10)\).
Short Answer
Expert verified
The slope of the line is the derivative at that point: \( f'(10) \).
Step by step solution
01
Understand the Problem
The problem states that when we zoom in closely on the graph of \( y = f(x) \) around \( x = 10 \) and observe a straight line, the slope of that line is the derivative \( f'(10) \). We need to determine what this graphical behavior implies.
02
Identify the Graphical Representation
Zooming in on a graph until it appears as a straight line means we are observing the tangent to the function at that point. This is a way of visualizing the derivative, as the tangent line represents the instantaneous rate of change of the function at a particular point.
03
Connect Graphical Representation to Derivative
The slope of the tangent line at a point on the graph of a function is defined as the derivative of the function at that point. Therefore, when the graph appears as a straight line near \( x = 10 \), its slope is \( f'(10) \).
04
Conclude with the Analytical Definition
The derivative \( f'(x) \) at a specific point \( x = a \) is calculated by the limit: \( f'(a) = \lim_{{h \to 0}} \frac{f(a+h) - f(a)}{h} \). If the graph straightens to a line as described, this corresponds to \( f'(10) \), the slope of that line.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Tangent Line
A tangent line is a straight line that just "touches" a curve at a particular point. This line provides an approximation of the curve's behavior right at that specific point. When you zoom in really close on a curve around a point, the curve may look just like a line. That line is the tangent line.
- It gives the best linear approximation to the function near the specific point.
- Only touches the curve at that one point of tangency.
- Shows the direction in which the curve moves.
Slope
The term "slope" refers to how steep a line is. Mathematically, slope is expressed as "rise over run," or the ratio of vertical movement to horizontal movement between two points. In the context of a tangent line to a curve, the slope is crucial because:
- It tells us how fast the function's value (y-coordinate) is changing at a specific point (x-coordinate).
- A greater slope means a steeper incline or decline.
- A positive slope indicates an upward trend, while a negative slope indicates a downward trend.
Instantaneous Rate of Change
Instantaneous rate of change is a critical concept that tells us how a quantity is changing at a specific moment. This is somewhat like looking at the speedometer of a car to see how fast you're going at a single point in time. Rather than calculating across an interval, it measures the rate at a single point.
- Equivalent to the slope of the tangent line for a function at a given point.
- Gives the exact rate at which the function value is altering.
- In calculus, it is represented by the derivative.
Limit Definition of Derivative
The limit definition of a derivative provides a formal method for finding the derivative, or instantaneous rate of change, of a function at any given point. It is denoted as:\[ f'(a) = \lim_{{h \to 0}} \frac{f(a+h) - f(a)}{h}\]This definition helps us calculate the derivative precisely:
- "f(a+h) - f(a)" represents the change in function values as you move from "a" to "a+h".
- "h" is the small change in the input value, approaching zero.
- The limit process is used to find the exact rate of change as the interval becomes infinitesimally small.