1. ## differentiation

i have to differentiate this using the quotient rule...and i tried to do it but ended up with something that really, really does not look right...i'm wondering if anyone can help please? i know i know how to do this but i dont seem to be able to for some reason!
thanks

y = x/(9 + x squared)

dy = ???
dx

2. Originally Posted by Oranges&Lemons
i have to differentiate this using the quotient rule...and i tried to do it but ended up with something that really, really does not look right...i'm wondering if anyone can help please? i know i know how to do this but i dont seem to be able to for some reason!
thanks

y = x/(9 + x squared)

dy = ???
dx
Hello,

$f(x)=\frac{x}{9+x^2}$ then using quotient rule

$f'(x) = \frac{(9+x^2)\cdot 1 - x \cdot 2x}{(9+x^2)^2}=\frac{9-x^2}{(9+x^2)^2}$

3. Originally Posted by earboth
Hello,

$f(x)=\frac{x}{9+x^2}$ then using quotient rule

$f'(x) = \frac{(9+x^2)\cdot 1 - x \cdot 2x}{(9+x^2)^2}=\frac{9-x^2}{(9+x^2)^2}$
thankyou! i did actually get that...but then i tried to multiply it out for some odd reason..and got a really long answer! oops, my bad. its nice to know you got the same as me though. thanks again.