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\(\frac{d}{dx}(x^{x})=?\)

  • A.\(x \ln x\)
  • B.\(x^{x}(1 + \ln x)\)
  • C.\(x^{x-1}\)
  • D.\(\ln x\)

Answer: B

The derivative is \(x^{x}(1 + \ln x)\).

Neither the power rule nor the exponential rule applies, because both the base and the exponent vary. Take logarithms first:

\[ \begin{aligned} y &= x^{x} \\ \ln y &= x\ln x \\ \frac{1}{y}\frac{dy}{dx} &= \ln x + 1 \\ \frac{dy}{dx} &= x^{x}(1 + \ln x) \end{aligned} \]

xx-1 wrongly treats the exponent as a constant (power rule), x ln x is ln y itself, and ln x is only part of the derivative of x ln x.

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