BF2S Forums Calculus Help

dYn.\ Finray: http://forums.bf2s.com/viewtopic.php?pi … 7#p2766857
dYn.\ Finray: njoi
liquidat0r: if x is 0
liquidat0r: srtc(1+x)
liquidat0r: = 1
dYn.\ Finray: don't care
dYn.\ Finray: post it there
dYn.\ Finray:
liquidat0r: i banned myself
liquidat0r: lol

liquidat0r: fuck
liquidat0r: i can't rmember limits properly
liquidat0r: oh, wait
liquidat0r: ok
liquidat0r: tell him to differentiate top and bottom
liquidat0r: so that you end up with
liquidat0r: 1 all over:
liquidat0r: -0.5(1+x)^-0.5
liquidat0r: and then put x = 0 in
liquidat0r: and you get -2
liquidat0r: paste this to that thread

Why the hell did Liq ban himself, what a drama-whore.

'Needed to do something' = acquire life?

Why is he still on Xfire then?

Psht...

can you tell him to get on steam?  i dont have xfire atm and i was looking for him on steam

wolfram alpha helps out alot

You can only use L'Hopital's rule if by subbing in x = 0 you get 0/0.

Since in this question you will get 0/(1-1) = 0/0, differentiate top and bottom and sub x = 0 into it again. If it still doesn't work, differentiate again and sub.

If all else fails, change the question from lim x -> 0 to lim y -> infinite with y = 1/x.

Last edited by Vub (2009-08-22 21:02:40)

Vub wrote:

You can only use L'Hopital's rule if by subbing in x = 0 you get 0/0.

Since in this question you will get 0/(1-1) = 0/0, differentiate top and bottom and sub x = 0 into it again. If it still doesn't work, differentiate again and sub.

If all else fails, change the question from lim x -> 0 to lim y -> infinite with y = 1/x.

It's saying when x approaches zero what is the limit of y. X does not equal 0.

x->0, x/(1-sqrt(1+x)) is -2

X->0^- (ie x=-0.000001)

-0.000001/(1-sqrt(1+-0.000001) = -2

X->0⁺ (ie x=0.000001)

0.000001/(1-sqrt(1+0.000001) = -2

Therefore the limit exists as x-> 0 from both sides so the limit is -2.

Using Dirv:


       X
-------------
1 - sqrt(1+X)

Put bottom on top to the ^-1.

X (1- sqrt(1+X)^-1

Chain rule:

f(u) = x
f(v) = (1-sqrt(1+X)^-1

f'(x) = f(u)f'(v) + f'(u)(fv)

f'(x) = (x) (-1(1- sqrt(1+X)^-2) (1 - sqrt(1+x) + (1)(1-sqrt(1+x)^-1

Unless I'm missing something obvious, using both Derivitives and First Principles still makes this question ludicrous. I've never delt with first principles past 1/x, having x in both is

Oisín<3 wrote:

learn2mathsguyz.

Theres no letters in maths,.

The art of wit is determined largely by your audience.

DrunkFace wrote:

Geez you make simple things difficult. BTW you don't need any calculus. (Look 3 posts up)

I'm sorry but in a mathematical proof of limits where you sub x = 0.00000000000001 into your calculator you won't get very far because that is not a proof.

Trust me, you have to sub x = 0 into the expression after differentiating the top and bottom, and if it gives you a sensible answer then that's the solution.

Also, when I said y -> infinite, I meant converting your x variable into a y variable, this way can help you solve some problems involving natural logarithms.

OK:

lim x-> 0 of x/(1-sqrt(1+x))

= lim x->0 of       1                             differentiate top and bottom
                   ---------------
                       -     1
                      -----------
                       2 sqrt(1+x)                  sub x = 0
= 1/(-1/2)
= -2

Last edited by Vub (2009-08-23 08:28:18)

Hakei wrote:

10x - 10x = 5x

wat