# absolute extreme values?

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• Sep 8th 2007, 09:01 PM
runner07
absolute extreme values?
What does it mean to find the absolute extreme values?

y= -5coshx + 4sinhx
• Sep 8th 2007, 09:03 PM
Jhevon
Quote:

Originally Posted by runner07
What does it mean to find the absolute extreme values?

y= -5coshx + 4sinhx

find the extreme values. the largest one (the absolute max) and the smallest one (the absolute min) are the ones you're after.

you do remember how to find extreme values right?
• Sep 8th 2007, 09:14 PM
runner07
do you make it equal to 0 and solve for x?
• Sep 8th 2007, 09:17 PM
Jhevon
Quote:

Originally Posted by runner07
do you make it equal to 0 and solve for x?

you set the derivative = 0 and solve for x, and state the f(x) for that (or those) x's. you also have to check the end points as well
• Sep 9th 2007, 10:48 AM
runner07
so itd be...

y'= 5sinhx + 4coshx =0 ?
• Sep 9th 2007, 11:05 AM
Jhevon
Quote:

Originally Posted by runner07
so itd be...

y'= 5sinhx + 4coshx =0 ?

no, $\frac {d}{dx} \cosh x = \sinh x$
• Sep 9th 2007, 11:07 AM
runner07
sorry, but i dont understand how you got that..
• Sep 9th 2007, 11:23 AM
topsquark
Quote:

Originally Posted by Jhevon
no, $\frac {d}{dx} \cosh x = \sinh x$

Quote:

Originally Posted by runner07
sorry, but i dont understand how you got that..

$cosh(x) = \frac{e^x + e^{-x}}{2}$

So
$\frac {d}{dx} \cosh x = \frac{d}{dx} \frac{e^x + e^{-x}}{2} = \frac{e^x - e^{-x}}{2} = sinh(x)$

-Dan