Math Problem Statement

Find the minimum and maximum values of the function y = x^3 - 24 ln(x) + 1 on the interval [1/2, 3] by comparing values at the critical points and endpoints.

Solution

To solve this problem, we need to find the minimum and maximum values of the function y=x324ln(x)+1y = x^3 - 24 \ln(x) + 1 on the interval [12,3]\left[ \frac{1}{2}, 3 \right]. Here’s the step-by-step approach:

  1. Calculate the derivative to find the critical points: y=ddx(x324ln(x)+1).y' = \frac{d}{dx} \left( x^3 - 24 \ln(x) + 1 \right). Using the power rule and the derivative of ln(x)\ln(x): y=3x224x.y' = 3x^2 - \frac{24}{x}.

  2. Set the derivative equal to zero to find critical points: 3x224x=0.3x^2 - \frac{24}{x} = 0. Multiply through by xx to clear the fraction: 3x324=0.3x^3 - 24 = 0. Solving for xx: x3=8x=2.x^3 = 8 \Rightarrow x = 2. So, x=2x = 2 is a critical point within the interval [12,3]\left[ \frac{1}{2}, 3 \right].

  3. Evaluate the function at the endpoints and the critical point:

    • At x=12x = \frac{1}{2}: y(12)=(12)324ln(12)+1.y\left( \frac{1}{2} \right) = \left( \frac{1}{2} \right)^3 - 24 \ln\left( \frac{1}{2} \right) + 1. Simplifying this, we get: y(12)=18+24ln(2)+1.y\left( \frac{1}{2} \right) = \frac{1}{8} + 24 \ln(2) + 1.

    • At x=2x = 2: y(2)=2324ln(2)+1=824ln(2)+1=924ln(2).y(2) = 2^3 - 24 \ln(2) + 1 = 8 - 24 \ln(2) + 1 = 9 - 24 \ln(2).

    • At x=3x = 3: y(3)=3324ln(3)+1=2724ln(3)+1=2824ln(3).y(3) = 3^3 - 24 \ln(3) + 1 = 27 - 24 \ln(3) + 1 = 28 - 24 \ln(3).

  4. Compare the values at x=12x = \frac{1}{2}, x=2x = 2, and x=3x = 3 to determine the minimum and maximum values.

  • Minimum: The smallest of ( y\left(

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Math Problem Analysis

Mathematical Concepts

Calculus
Critical Points
Interval Analysis

Formulas

y' = 3x^2 - 24/x

Theorems

Extreme Value Theorem

Suitable Grade Level

Grades 11-12