# Thread: absolute extreme values?

1. ## absolute extreme values?

What does it mean to find the absolute extreme values?

y= -5coshx + 4sinhx

2. 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?

3. do you make it equal to 0 and solve for x?

4. 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

5. so itd be...

y'= 5sinhx + 4coshx =0 ?

6. Originally Posted by runner07
so itd be...

y'= 5sinhx + 4coshx =0 ?
no, $\frac {d}{dx} \cosh x = \sinh x$

7. sorry, but i dont understand how you got that..

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