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[SOLVED] 3.1.008 absolute max value

karush

Well-known member
Jan 31, 2012
2,678
Let f be the function defined by
$f(x)=\dfrac{\ln x}{x}$ What is the absolute minimum value of f
a, 1
b. $\dfrac{1}{e}$
c. 0
d. e
e. none

ok I assume we take the derivative and then set it to zero

$\frac{1-\ln\left(x\right)}{x^{2}}=0$
$x=e$
 
Last edited:

skeeter

Well-known member
MHB Math Helper
Mar 1, 2012
655
ok I assume we take the derivative and then set it to zero

then set that into f(x)

I think it is (B)
how do you know it’s not a minimum?
 

HallsofIvy

Well-known member
MHB Math Helper
Jan 29, 2012
1,151
ok I assume we take the derivative and then set it to zero

then set that into f(x)

I think it is (B)
Okay, what do you get when you take the derivative? What x value makes that equal to 0? In other words, tell us why you "think it is (B)!