Math Problem Statement

Solve B, looking carefully at the powers in the function

Use the Intermediate Value Theorem to determine whether or not there is a value c in the interval [2, 8] such that f(c) = 4/3.

Solution

Let's focus on solving part b of the problem. To do that, we need to apply the Intermediate Value Theorem (IVT).

Restating Part B:

  • We are given f(x)f(x) in two pieces:
    • f(x)=x1f(x) = \sqrt{x - 1} for 1x51 \leq x \leq 5
    • f(x)=3x5x3+1f(x) = \frac{3x - 5}{x^3 + 1} for 5<x105 < x \leq 10
  • The goal is to find whether there exists some c[2,8]c \in [2, 8] such that f(c)=43f(c) = \frac{4}{3}, using the Intermediate Value Theorem (IVT).

Steps:

  1. Check if f(x)f(x) is continuous on the interval [2, 8]: The Intermediate Value Theorem requires that the function is continuous on the closed interval. We know that f(x)f(x) is composed of two parts, each defined on different intervals:

    • f(x)=x1f(x) = \sqrt{x - 1} is continuous for x1x \geq 1, including on [2,5][2, 5].
    • f(x)=3x5x3+1f(x) = \frac{3x - 5}{x^3 + 1} is also continuous for x(5,10]x \in (5, 10]. Therefore, f(x)f(x) is continuous on [2,8][2, 8] because there are no discontinuities at x=5x = 5 (based on part a).
  2. Evaluate the function at the endpoints: We need to check the values of f(2)f(2) and f(8)f(8) to see if f(c)=43f(c) = \frac{4}{3} lies between these values.

    • For x=2x = 2, f(2)=21=1=1f(2) = \sqrt{2 - 1} = \sqrt{1} = 1.
    • For x=8x = 8, f(8)=3(8)583+1=245512+1=195130.037f(8) = \frac{3(8) - 5}{8^3 + 1} = \frac{24 - 5}{512 + 1} = \frac{19}{513} \approx 0.037.
  3. Check if f(c)=43f(c) = \frac{4}{3} is between f(2)f(2) and f(8)f(8): We see that:

    • f(2)=1f(2) = 1
    • f(8)0.037f(8) \approx 0.037

    Since 431.333\frac{4}{3} \approx 1.333, it is not between f(2)=1f(2) = 1 and f(8)0.037f(8) \approx 0.037. Therefore, by the Intermediate Value Theorem, there is no such c[2,8]c \in [2, 8] such that f(c)=43f(c) = \frac{4}{3}.

Conclusion:

There does not exist a value c[2,8]c \in [2, 8] such that f(c)=43f(c) = \frac{4}{3} based on the given function.


Do you have any questions or want further details on this solution? Here are 5 questions you could explore:

  1. How would the IVT apply if the value 43\frac{4}{3} were within the range of f(x)f(x) on the interval?
  2. How can you prove that f(x)f(x) is continuous at x=5x = 5?
  3. What happens to the function as xx approaches values near 1 or near 10?
  4. Can you calculate the precise value of f(x)f(x) for x=8x = 8 using a calculator?
  5. What other intervals might satisfy the Intermediate Value Theorem for different target values of f(x)f(x)?

Tip: Always check the continuity of the function first when applying the Intermediate Value Theorem!

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Math Problem Analysis

Mathematical Concepts

Continuity
Intermediate Value Theorem
Piecewise Functions

Formulas

f(x) = sqrt(x - 1) for 1 <= x <= 5
f(x) = (3x - 5) / (x^3 + 1) for 5 < x <= 10

Theorems

Intermediate Value Theorem

Suitable Grade Level

Undergraduate - Calculus