Math Problem Statement

Find the absolute maximum and absolute minimum values of f on the given interval. f(x) = x−2 ln(x),

1 2 , 6

absolute minimum value

absolute maximum value

Solution

To find the absolute maximum and minimum values of the function f(x)=x2ln(x)f(x) = x - 2\ln(x) on the interval [12,6]\left[\frac{1}{2}, 6\right], follow these steps:

  1. Find the critical points of f(x)f(x):

    First, find the derivative f(x)f'(x) and set it equal to zero to find the critical points. f(x)=x2ln(x)f(x) = x - 2 \ln(x) f(x)=12xf'(x) = 1 - \frac{2}{x} Set the derivative equal to zero: 12x=01 - \frac{2}{x} = 0 Solve for xx: 2x=1\frac{2}{x} = 1 x=2x = 2

  2. Evaluate f(x)f(x) at the critical points and endpoints of the interval:

    The critical point is x=2x = 2. The endpoints of the interval are x=12x = \frac{1}{2} and x=6x = 6.

    f(12)=122ln(12)=122(ln(2))=12+2ln(2)f\left(\frac{1}{2}\right) = \frac{1}{2} - 2 \ln\left(\frac{1}{2}\right) = \frac{1}{2} - 2(-\ln(2)) = \frac{1}{2} + 2 \ln(2) f(2)=22ln(2)f(2) = 2 - 2 \ln(2) f(6)=62ln(6)f(6) = 6 - 2 \ln(6)

  3. Compare the values to find the absolute maximum and minimum:

    Calculate the values: f(12)=12+2ln(2)0.5+20.693=0.5+1.386=1.886f\left(\frac{1}{2}\right) = \frac{1}{2} + 2 \ln(2) \approx 0.5 + 2 \cdot 0.693 = 0.5 + 1.386 = 1.886 f(2)=22ln(2)220.693=21.386=0.614f(2) = 2 - 2 \ln(2) \approx 2 - 2 \cdot 0.693 = 2 - 1.386 = 0.614 f(6)=62ln(6)621.792=63.584=2.416f(6) = 6 - 2 \ln(6) \approx 6 - 2 \cdot 1.792 = 6 - 3.584 = 2.416

    Therefore: f(12)1.886f\left(\frac{1}{2}\right) \approx 1.886 f(2)0.614f(2) \approx 0.614 f(6)2.416f(6) \approx 2.416

    So, the absolute minimum value is f(2)0.614f(2) \approx 0.614 and the absolute maximum value is f(6)2.416f(6) \approx 2.416.

To summarize:

  • Absolute minimum value: 0.614\approx 0.614 at x=2x = 2
  • Absolute maximum value: 2.416\approx 2.416 at x=6x = 6

Would you like further details or have any questions?

Here are 5 additional questions you might ask:

  1. How do you find the derivative of a function?
  2. What is the second derivative test for concavity?
  3. How do you solve logarithmic equations?
  4. What are the properties of logarithms?
  5. Can you explain the concept of critical points in calculus?

Tip: When solving for critical points, always check the function's endpoints within the given interval to ensure you find the absolute maximum and minimum values.

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Math Problem Analysis

Mathematical Concepts

Calculus
Derivatives
Logarithmic functions

Formulas

Derivative of f(x)
Natural logarithm properties

Theorems

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Suitable Grade Level

Advanced Mathematics