MCQ
વિધેય $ = \,\,\frac{x}{{\ln \,x}}$ ક્યાં અંતરાલમાં વધતું હોય $?$
- A$(-\infty , 0)$
- ✓$(e, \infty )$
- C$(0, \infty )$
- D$(-\infty , e)$
${f'}(x)\,\, = \,\,\frac{{\log \,x\,\, - \,\,x\,.\,\frac{1}{x}}}{{{{(\log \,x)}^2}}}$
${f}(x)\,$ માટે વધતું વિધેય હોય,
તો ${f'}{\rm{(x)}}\,\, > \,\,{\rm{0}}$
$ \Rightarrow \,\,\frac{{{\rm{log}}\,\,{\rm{x}}\,\,{\rm{ - }}\,\,{\rm{1}}}}{{{{{\rm{(log}}\,\,{\rm{x)}}}^{\rm{2}}}}}\,\, > \,\,0\,\,\,\,\,\,$
$ \Rightarrow \,\,\log \,\,x\,\, > \,\,1\,\,\,\,\, $
$\Rightarrow \,\,x\,\, > \,\,e\,\,\,\,\,\, $
$\Rightarrow \,\,x\,\, \in \,\,(e,\,\,\infty )$
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