For example,

if f(x)=x^9+4x^3+3x, find the second derivative f " (x).

im so confused...i honestly have no idea

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- Oct 8th 2008, 04:57 AMjemadd2How do you find the second derivative?
For example,

if f(x)=x^9+4x^3+3x, find the second derivative f " (x).

im so confused...i honestly have no idea - Oct 8th 2008, 05:14 AMgidget
$\displaystyle f(x)=x^9+4x^3+3x$

to find the second derivative, you simply take the first derivative, then from that result do the exact same thing to get the second.

$\displaystyle f'(x)= 9x^8 + 12x^2 +3$

$\displaystyle f''(x) = 72x^7 + 24x $ - Oct 8th 2008, 05:16 AMGreengoblin
Remember the derivative of a function f(x)

*is another function*(The 'Gradient function'), denoted f '(x), so all you do is take the derivative of this function to get the 'second derivative,' f''(x)....so it's as easy as that - differentiate twice. Think you can do it now?

edit: beaten to the mark :) - Oct 8th 2008, 05:33 AMjemadd2
yes....thank you both very much