wow, derivitaves suck

[liebherk]

calculus is haaard...

let f(x) = 3x^2 + 6/x^2

find the derivitave at -6.

[one_armed_boxer]

i dont know what that is :(

il help you out next year... ha

[fat_poser]

working on it...will post results in a sec

let f(x) = 3x^2 + 6/x^2

find the derivitave at -6.

ok idunno if you know the power rule
so first figure out the general equation of f prime at x

f'(x) = 3(2)x^1 + 6(2) / x^1

You multiply the exponent/degree by the coefficient to get the new coefficient, and subtract 1 from the exponent to get the new exponent

so

f'(x) = 6x + 12/x

The derivative will always be 1 degree lower than f(x)

So to find f'(-6), you simply substitute -6 for x in the derivatives general equation

f'(-6) = 6(-6) + 12 / (-6)
f'(-6) = -36 - 2
f'(-6) = -38

Hope that was helpful

[Edited on 23-9-2005 by fat_poser]

[scott123]

3x^2 + 6 / (x^2) <-- hopes i got parenthesis right.

first apply power rule to first side

6x+ derivative of 6/(x^2)

then apply quotient rule to next side, [bottom*d(top) - top* d(bottom)] / bottom^2:

-12x/ x^4

so you get : 6x- 12x/ x^4
simplify to : 6x-12/x^3
plug in -6 for x.
(-647 / 18 )

if you ever need any calc help, post here and ill help or you can u2u or im me if you need better explination.

to fat_poser: you can apply the power rule like that on the fractional part.

[Edited on 23-9-2005 by scott123]

[fat_poser]

oh shit

i did it like (6/x)^2, instead of 6 over x squared [ 6/(x^2) ]

thats the problem with using text to do calculus, shit isn't very clear

f(x) = 3x^2 + 6/x^2

that couldve been either one

but if it is 6/(x^2) scott is right you need to quotient rule that motherfucker

[Edited on 23-9-2005 by fat_poser]

[usuckhugeonez]

dude im in fucking pre-algebra...hah

[scott123]

Originally posted by usuckhugeonez
dude im in f**king pre-algebra...hah

why would you post this?

and fat_poser, if you were to do it like (6/x)^2, you would need to use the chain rule not the power rule.

[Edited on 23-9-2005 by scott123]

[fat_poser]

correct again
fuck my math is rusty

[Tomiger RoPort]

Originally posted by scott123
Originally posted by usuckhugeonez
dude im in f**king pre-algebra...hah

why would you post this?

and fat_poser, if you were to do it like (6/x)^2, you would need to use the chain rule not the power rule.

[Edited on 23-9-2005 by scott123]

Now show me a vertical shift

[fat_poser]

only if you show me a point of inflection

[Tomiger RoPort]

haha, that was a little inside joke. I am in 10th grade, taking trig, blah blah, and i asked scott on AIM a question about vertical shifts of the graphs on sins and cosines and it took us like 30 minutes to remember it right, it was so funny.

[one_armed_boxer]

im in intermidiate college algebra.. nothing hard.. its so easy to the point where it pisses me off. Mostly bc its all been review lately.. graphing on two dimensional planes in point slope form.. that kinda stuff.

[Tomiger RoPort]

Originally posted by one_armed_boxer
im in intermidiate college algebra.. nothing hard.. its so easy to the point where it pisses me off. Mostly bc its all been review lately.. graphing on two dimensional planes in point slope form.. that kinda stuff.

Yeah me and my brother are doing our own little course of college algebra, I meet at his place on Wednesdays and go over the Schuam's outline thing we have, so far it's just review and more detailed explainations of older things, like factoring and crap.

[scott123]

vertical shifts didnt take me long to remember! it was dividing polynomials that did.

[Tomiger RoPort]

Originally posted by scott123
vertical shifts didnt take me long to remember! it was dividing polynomials that did.

we it's not that vertical shifts took long to remember, but it took a while for us to both argree on the right way

[Agent]

Originally posted by scott123
Originally posted by usuckhugeonez
dude im in f**king pre-algebra...hah

why would you post this?

and fat_poser, if you were to do it like (6/x)^2, you would need to use the chain rule not the power rule.

[Edited on 23-9-2005 by scott123]

I would just use quotient and distribute the square.. chain rule is gay.. it admitted it to me one time.

[skaterbob]

actually , im not sure if what you said is correct, i think you need to do the chain rule AND the quotient rule combined, yeah , uhh , just do the chain rule and when you have to find the derivative of the inside, use the quotient rule

[scott123]

if its (6/x)^2 you need chain if its 6/(x^2) you dont.

http://img321.imageshack.us/img321/4987/cocks9hh.gif (http://imageshack.us)