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Ravus
Group Title
derivative of:
sqrt(x)  x
using the first principal. Please show work. The answer should be 1/[2*sqrt(x)]1
I cant get the minus 1!
 2 years ago
 2 years ago
Ravus Group Title
derivative of: sqrt(x)  x using the first principal. Please show work. The answer should be 1/[2*sqrt(x)]1 I cant get the minus 1!
 2 years ago
 2 years ago

This Question is Open

experimentX Group TitleBest ResponseYou've already chosen the best response.0
i guess you know how to find the derivate of x ... so just find for sqrt(x)
 2 years ago

Ravus Group TitleBest ResponseYou've already chosen the best response.0
f(x) = \[\sqrt{x} x \]
 2 years ago

Ravus Group TitleBest ResponseYou've already chosen the best response.0
oh...so just do them one at a time?: That actually makes a lot of sense. the problem is I have the equation in the "definition of the derivative formula" and its not simplifying down right.
 2 years ago

Ravus Group TitleBest ResponseYou've already chosen the best response.0
where you take the limit as h>0
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.0
lim dx>0 (sqrt(x+dx)  sqrt(x))/dx now sqrt(x+dx) = sqrt(x)*sqrt(1+dx/x) using binomial expansion, and removing higher terms  close to linear expression we have: sqrt(x)(1+1/2*dx/x) or, lim dx>0 (sqrt(x)(1+1/2*dx/x)  sqrt(x))/dx or, lim dx>0 (1/2*dx/sqrt(x))/dx = 1/(2sqrt(x)) hence proved
 2 years ago

lgbasallote Group TitleBest ResponseYou've already chosen the best response.0
seems he wants the increment thingy...the limits
 2 years ago

dpaInc Group TitleBest ResponseYou've already chosen the best response.1
@Ravus , are you asking to take the derivative using the definition? (limit definition of derivative)
 2 years ago

perl Group TitleBest ResponseYou've already chosen the best response.0
@experimentX how do you get this sqrt(x+dx) = sqrt(x)*sqrt(1+dx/x)
 2 years ago

dpaInc Group TitleBest ResponseYou've already chosen the best response.1
@perl, nice avatar!
 2 years ago

Ravus Group TitleBest ResponseYou've already chosen the best response.0
yes I want the "increment thingy"<<<thats exactally it! and yes dpalnc, I think it is the limit definition I mean.
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.0
@perl .. take x common!
 2 years ago

dpaInc Group TitleBest ResponseYou've already chosen the best response.1
dw:1333351654824:dw plug it in to that...
 2 years ago

perl Group TitleBest ResponseYou've already chosen the best response.0
(x+dx)^1/2 = x^1/2 + ...
 2 years ago

Ravus Group TitleBest ResponseYou've already chosen the best response.0
yeah I did plug it in, and I get the right answer almost. I get 1/2*sqrt(x) but that whole thing should have a "1"! i dont get that bit
 2 years ago

perl Group TitleBest ResponseYou've already chosen the best response.0
@experimentX (x+dx)^1/2 = x^1/2 ( 1 + dx/x ) ^1/2
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.0
dx is supposed to be del x ... or better h
 2 years ago

dpaInc Group TitleBest ResponseYou've already chosen the best response.1
dw:1333351804706:dw do some algebra here....
 2 years ago

dpaInc Group TitleBest ResponseYou've already chosen the best response.1
ok... too many cooks... i'll quit.
 2 years ago

Ravus Group TitleBest ResponseYou've already chosen the best response.0
yeah I know what the formula is, but the algebra is giving me trouble
 2 years ago

perl Group TitleBest ResponseYou've already chosen the best response.0
@experimentX Very clever argument, so you looked at the binomial series and took the first two terms (linear )
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.0
yes .. since dx^higer would be very less ... it would seem better to take linear term.
 2 years ago

perl Group TitleBest ResponseYou've already chosen the best response.0
then you factored out sqrt x
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.0
yes .. and that would cancel out .. sqrt(x) leaving dx/(2sqrt(x)
 2 years ago

Ravus Group TitleBest ResponseYou've already chosen the best response.0
omg wow finally got it. simple algebra really. lmfao............
 2 years ago

experimentX Group TitleBest ResponseYou've already chosen the best response.0
congrats
 2 years ago

gurvinder Group TitleBest ResponseYou've already chosen the best response.0
dw:1333354174909:dw
 2 years ago
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