The derivative of $(\log x)^x$ with respect to $\log x$ is |
$x(\log x)^x [1+ \log x.\log(\log x)]$ $x(\log x)^x [x+1+\log x.\log(\log x)]$ $x(\log x)^{x-1} [1+ \log x.\log(\log x)]$ $(\log x)^{x-1} [1+ \log x.\log(\log x)]$ |
$x(\log x)^x [1+ \log x.\log(\log x)]$ |
The correct answer is Option (1) → $x(\log x)^x [1+ \log x.\log(\log x)]$ ** Given function: $y = (\log x)^x$ Taking $\ln$: $\ln y = x \ln(\log x)$ Differentiate w.r.t. $x$: $\frac{1}{y}\frac{dy}{dx} = \ln(\log x) + x\cdot \frac{1}{\log x}\cdot \frac{1}{x}$ $\frac{dy}{dx} = (\log x)^x\left[\ln(\log x) + \frac{1}{\log x}\right]$ Now derivative w.r.t. $\log x$: $\frac{dy}{d(\log x)} = x\cdot \frac{dy}{dx}$ $= x(\log x)^x\left[\ln(\log x) + \frac{1}{\log x}\right]$ Factor into required option form: $= x(\log x)^x\left[1 + \log x \cdot \ln(\log x)\right]$ The derivative is $x(\log x)^x\left[1 + \log x \cdot \ln(\log x)\right]$. |