Math Problem Statement

The graph of the function f and a table of selected values of f(x) are shown. Approximate f'(4.5), find if there’s a value of x for which the derivative is zero, and evaluate three different limit expressions at x = 5.

Solution

Let's work through the given AP Calculus problem step by step.

Problem Overview:

The graph of a function ff is given, alongside a table of selected values of f(x)f(x). The graph and the table offer information about the behavior of the function around specific points.

We are asked to address the following parts: (a) Approximate the value of f(4.5)f'(4.5) using data from the table. (b) Determine if there is a value of xx, for 0<x<50 < x < 5, such that limh0f(x+h)f(x)h=0\lim_{h \to 0} \frac{f(x+h) - f(x)}{h} = 0. (c) Evaluate three different limit expressions.


Part (a): Approximate f(4.5)f'(4.5)

To approximate f(4.5)f'(4.5), we'll use the definition of the derivative: f(4.5)f(x2)f(x1)x2x1f'(4.5) \approx \frac{f(x_2) - f(x_1)}{x_2 - x_1} We can use values of f(x)f(x) near x=4.5x = 4.5 from the table.

From the table, we have: f(4)=2.533andf(5)=1f(4) = 2.533 \quad \text{and} \quad f(5) = 1

Now, calculate the average rate of change between x=4x = 4 and x=5x = 5: f(4.5)f(5)f(4)54=12.5331=1.533f'(4.5) \approx \frac{f(5) - f(4)}{5 - 4} = \frac{1 - 2.533}{1} = -1.533 So, f(4.5)1.533f'(4.5) \approx -1.533.


Part (b): Is there a value xx such that limh0f(x+h)f(x)h=0\lim_{h \to 0} \frac{f(x+h) - f(x)}{h} = 0?

The expression given is the definition of the derivative, f(x)f'(x). The question asks if there is a value of xx for which the derivative is equal to zero.

From the graph, a horizontal tangent (which indicates f(x)=0f'(x) = 0) occurs at x=2x = 2, as stated in the problem description.

Therefore, the value of xx where f(x)=0f'(x) = 0 is x=2x = 2.


Part (c): Evaluate the given limits

  1. limh0+f(5+h)f(5)h\lim_{h \to 0^+} \frac{f(5+h) - f(5)}{h}

    This limit represents the right-hand derivative at x=5x = 5. Using the table, we have:

    • f(5)=1f(5) = 1
    • f(5.5)=1.125f(5.5) = 1.125

    Approximate the derivative: f(5.5)f(5)5.55=1.12510.5=0.25\frac{f(5.5) - f(5)}{5.5 - 5} = \frac{1.125 - 1}{0.5} = 0.25

    So, limh0+f(5+h)f(5)h=0.25\lim_{h \to 0^+} \frac{f(5+h) - f(5)}{h} = 0.25.

  2. limh0f(5+h)f(5)h\lim_{h \to 0^-} \frac{f(5+h) - f(5)}{h}

    This limit represents the left-hand derivative at x=5x = 5. Using the table, we have:

    • f(5)=1f(5) = 1
    • f(4.5)=3.193f(4.5) = 3.193

    Approximate the derivative: f(4.5)f(5)4.55=3.19310.5=2.1930.5=4.386\frac{f(4.5) - f(5)}{4.5 - 5} = \frac{3.193 - 1}{-0.5} = \frac{2.193}{-0.5} = -4.386

    So, limh0f(5+h)f(5)h=4.386\lim_{h \to 0^-} \frac{f(5+h) - f(5)}{h} = -4.386.

  3. limh0f(5+h)f(5)h\lim_{h \to 0} \frac{f(5+h) - f(5)}{h}

    Since the right-hand and left-hand derivatives at x=5x = 5 do not match, the derivative does not exist at x=5x = 5. Hence, this limit does not exist.


Conclusion:

  • (a) f(4.5)1.533f'(4.5) \approx -1.533
  • (b) f(2)=0f'(2) = 0, so the value of xx is 2.
  • (c)(i) limh0+f(5+h)f(5)h=0.25\lim_{h \to 0^+} \frac{f(5+h) - f(5)}{h} = 0.25
  • (c)(ii) limh0f(5+h)f(5)h=4.386\lim_{h \to 0^-} \frac{f(5+h) - f(5)}{h} = -4.386
  • (c)(iii) The limit does not exist.

Do you need more details on any part of this solution? Here are five related questions to explore this concept further:

  1. How do we know when to use a difference quotient to approximate a derivative?
  2. Why is the limit of the derivative different from the left and right at x=5x = 5?
  3. What is the significance of concavity and how does it affect derivative signs?
  4. How can we identify points where the derivative of a function is zero on a graph?
  5. What conditions cause the derivative of a function to not exist at a point?

Tip: When approximating derivatives from data points, make sure to select values of xx that are as close as possible to the point of interest to get a better approximation.

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Math Problem Analysis

Mathematical Concepts

Differentiation
Limits
Tangent Line
Concavity

Formulas

f'(x) ≈ (f(x+h) - f(x))/h (definition of derivative)
Right-hand limit: lim (h→0^+) (f(x+h) - f(x))/h
Left-hand limit: lim (h→0^-) (f(x+h) - f(x))/h

Theorems

Definition of Derivative
Tangent Line Theorem
Concavity and Inflection Points

Suitable Grade Level

Advanced Placement (AP) - High School