In which of the following interval the function $f(x) = x^x,x>0$ is strictly increasing? |
$[e,∞)$ $(\frac{1}{e},∞)$ $[1,∞)$ $[0,∞)$ |
$(\frac{1}{e},∞)$ |
The correct answer is Option (2) → $(\frac{1}{e},∞)$ Given function $f(x)=x^x,\ x>0$ Differentiating $f'(x)=x^x(\log x+1)$ For strictly increasing function $f'(x)>0$ $x^x(\log x+1)>0$ Since $x^x>0$ for $x>0$, condition becomes $\log x+1>0$ $\log x>-1$ $x>\frac{1}{e}$ Hence $f(x)$ is strictly increasing in $\left(\frac{1}{e},\infty\right)$ |