could someone help me with this: if y= 1/(x+1) find y'...

i tried and i got this equation x^2 +2x +1 is it correct???

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- Oct 26th 2008, 01:47 PMjuanfe_zodiacsimple derivative of...
could someone help me with this: if y= 1/(x+1) find y'...

i tried and i got this equation x^2 +2x +1 is it correct??? - Oct 26th 2008, 02:00 PMJhevon
- Oct 26th 2008, 02:40 PMjuanfe_zodiacsimple derivative of...
i still dont getting it...could u explain me...what chain is that? how do i know that the new derivative is correct?

- Oct 26th 2008, 02:47 PMRedBarchetta
$\displaystyle

\begin{gathered}

y = \frac{1}

{{x + 1}} \hfill \\

y' = ? \hfill \\

\end{gathered}

$

Use the quotient rule:

$\displaystyle

\left( {\frac{u}

{v}} \right)' = \frac{{u'v - uv'}}

{{v^2 }}

$

Where u=1 and v=x+1..... - Oct 26th 2008, 04:16 PMJhevon
the chain rule says: $\displaystyle \frac d{dx} f(g(x)) = f'(g(x)) \cdot g'(x)$

basically, to find the derivative of a composite function, differentiate the outer function (leaving the inner function intact) then multiply by the derivative of the inside function

$\displaystyle y = (x + 1)^{-1}$

$\displaystyle \Rightarrow y' = -(x + 1)^{-2}(1) = \frac {-1}{(x + 1)^2}$

as for knowing the derivative is correct, look up the answer in your text :D...or check it with integration, but i don't suppose you have started integration as yet