Practicing Success
If $\int\left\{\log (\log x)+\frac{1}{(\log x)^2}\right\} d x=x\{f(x)-g(x)\}+C$, then |
$f(x)=\log (\log x) ; g(x)=\frac{1}{\log x}$ $f(x)=\log x ; g(x)=\frac{1}{\log x}$ $f(x)=\frac{1}{\log x} ;(x)=\log (\log x)$ $f(x)=\frac{1}{x \log x} ; g(x)=\frac{1}{\log x}$ |
$f(x)=\log (\log x) ; g(x)=\frac{1}{\log x}$ |
We have, $I =\int\left\{\log (\log x)+\frac{1}{(\log x)^2}\right\} d x$ $\Rightarrow I =\int e^t\left(\log t+\frac{1}{t^2}\right) d t, \text { where } t=\log x$ $\Rightarrow I =\int e^t\left(\log t+\frac{1}{t}\right) d t+\int e^t\left(-\frac{1}{t}+\frac{1}{t^2}\right) d t$ $\Rightarrow I =e^t \log t+e^t\left(-\frac{1}{t}\right)+C$ $\Rightarrow I=x\left(\log (\log x)-\frac{1}{\log x}\right)+C$ ∴ $f(x)=\log(\log (x))$ and $g(x)=\frac{1}{\log x}$ |