# [SOLVED] Find Critical Points

• Feb 23rd 2010, 01:11 PM
vinson24
[SOLVED] Find Critical Points
$f(x)={ln(2x)}/{x} ;[1,e]$
Find the critical points
I used the quotient rule and got
$f'(x)= {-ln(2x)}/{x^{2}}$
and now i equal the equation to zero and them im stuck cant solve it
• Feb 23rd 2010, 01:15 PM
icemanfan
This is because

$f'(x) = \frac{1 - \ln (2x)}{x^2}$.

Try solving it now.
• Feb 23rd 2010, 01:26 PM
vinson24
Still not sure. Not sure how what to do with the ln(2x) and the $x^{2}$ on the bottom
• Feb 23rd 2010, 01:30 PM
icemanfan
The only way to get $\frac{1 - \ln (2x)}{x^2} = 0$ is to have $1 - \ln (2x) = 0$ or $\ln (2x) = 1$.
• Feb 23rd 2010, 01:38 PM
vinson24
So then I would only have on critical point on that interval?