Im struggling with finding the 1st and 2nd derivatives of these functions (Worried)

f(x)= tan^-1 3x

So far i have done:

dy/dx = 3 (1/1+(3x)^2) = 3/ (1+9x^2)

Im not sure where to go from there

Any help much appraciated.

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- May 18th 2009, 12:08 PMjamm89Help required: 1st and 2nd derivatives of functions
Im struggling with finding the 1st and 2nd derivatives of these functions (Worried)

f(x)= tan^-1 3x

So far i have done:

dy/dx = 3 (1/1+(3x)^2) = 3/ (1+9x^2)

Im not sure where to go from there

Any help much appraciated. - May 18th 2009, 12:17 PMJester
- May 18th 2009, 12:33 PMjamm89
$\displaystyle (3+27x^2)^{-1}$ so i use chain rule on this?

u=$\displaystyle 3+27x^2$ y=$\displaystyle u^-1$

du/dx = 54x dy/du= $\displaystyle -u^-2$

Can someone finish this off for me please as i have no idea where to go from here

thanks - May 18th 2009, 12:44 PMJester