Math Problem Statement

using the mean value theorem on the interval [6,14] find the value of c that satisfies the equation f'(c)=f(b)-f(a)/ b-a for the function ln(x-5)

Solution

The Mean Value Theorem (MVT) states that if a function f(x)f(x) is continuous on the closed interval [a,b][a, b] and differentiable on the open interval (a,b)(a, b), then there exists a number cc in (a,b)(a, b) such that:

f(c)=f(b)f(a)baf'(c) = \frac{f(b) - f(a)}{b - a}

Given Function:

f(x)=ln(x5)f(x) = \ln(x - 5)

Given Interval:

[ [a, b] = [6, 14] ]

Step 1: Check Conditions for MVT

  • The function f(x)=ln(x5)f(x) = \ln(x - 5) is defined and continuous for x>5x > 5, and differentiable for x>5x > 5.
  • Since the given interval [6,14][6, 14] is completely within this domain, the function satisfies the conditions of the MVT.

Step 2: Compute f(x)f'(x)

f(x)=1x5f'(x) = \frac{1}{x - 5}

Step 3: Compute the Average Rate of Change

f(b)f(a)ba=ln(145)ln(65)146\frac{f(b) - f(a)}{b - a} = \frac{\ln(14 - 5) - \ln(6 - 5)}{14 - 6}

=ln9ln18= \frac{\ln 9 - \ln 1}{8}

Since ln1=0\ln 1 = 0, we get:

=ln98= \frac{\ln 9}{8}

Step 4: Solve for cc

Using MVT:

1c5=ln98\frac{1}{c - 5} = \frac{\ln 9}{8}

Solving for cc:

c5=8ln9c - 5 = \frac{8}{\ln 9}

c=5+8ln9c = 5 + \frac{8}{\ln 9}

Final Answer:

c=5+8ln9c = 5 + \frac{8}{\ln 9}

Would you like a numerical approximation or a more detailed breakdown?

Related Questions:

  1. How do you prove the Mean Value Theorem?
  2. What are the conditions under which MVT does not apply?
  3. Can MVT be used on a function with a discontinuity? Why or why not?
  4. How does MVT relate to Rolle's Theorem?
  5. Can we apply MVT to absolute value functions? Why or why not?

Tip:

The Mean Value Theorem guarantees at least one cc, but there could be multiple values of cc that satisfy the condition. Always check for all possible solutions!

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Math Problem Analysis

Mathematical Concepts

Calculus
Mean Value Theorem
Differentiation
Natural Logarithms

Formulas

f'(c) = (f(b) - f(a)) / (b - a)
f'(x) = 1 / (x - 5)

Theorems

Mean Value Theorem

Suitable Grade Level

Grades 11-12