Math Problem Statement

If y = x^x, find the second derivative y''.

Solution

The problem asks for the second derivative of y=xxy = x^x. Here's the solution:

  1. Rewrite yy in logarithmic terms: y=xx=exlnx.y = x^x = e^{x \ln x}. Differentiating y=exlnxy = e^{x \ln x} using the chain rule gives: y=exlnxddx(xlnx).y' = e^{x \ln x} \cdot \frac{d}{dx}(x \ln x). Since exlnx=xxe^{x \ln x} = x^x, this simplifies to: y=xx(lnx+1).y' = x^x \cdot \left( \ln x + 1 \right).

  2. Find the second derivative yy'': Differentiate yy' again: y=xx(lnx+1).y' = x^x \cdot \left( \ln x + 1 \right). Using the product rule (uv)=uv+uv(uv)' = u'v + uv', we calculate:

    • u=xxu = x^x, so u=xx(lnx+1)u' = x^x (\ln x + 1),
    • v=(lnx+1)v = (\ln x + 1), so v=1xv' = \frac{1}{x}.

    Now substitute into the product rule: y=(xx(lnx+1))(lnx+1)+xx1x.y'' = \left( x^x (\ln x + 1) \right)(\ln x + 1) + x^x \cdot \frac{1}{x}. Simplify terms: y=xx(lnx+1)2+xx1.y'' = x^x (\ln x + 1)^2 + x^{x-1}.

Final Answer:

The correct option is: (c) y(1+lnx)2+xx1\boxed{(c) \ y(1 + \ln x)^2 + x^{x-1}}

Would you like a more detailed step-by-step explanation of any part?

Related Questions:

  1. How do you derive the derivative of exponential functions with variable exponents?
  2. Can logarithmic differentiation be applied to other forms of y=u(x)v(x)y = u(x)^{v(x)}?
  3. What are the differences between the product rule and chain rule?
  4. Why does exlnxe^{x \ln x} simplify to xxx^x?
  5. How do second derivatives help in analyzing functions?

Tip:

For functions like xxx^x, rewriting them in terms of exponential functions simplifies differentiation.

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Math Problem Analysis

Mathematical Concepts

Exponential Functions
Logarithmic Differentiation
Chain Rule
Product Rule

Formulas

y = x^x = e^{x ln x}
Product Rule: (uv)' = u'v + uv'
Chain Rule: (f(g(x)))' = f'(g(x)) * g'(x)

Theorems

Derivative of Exponential Functions
Properties of Logarithms

Suitable Grade Level

Grades 11-12