# Thread: Find the first and second derivatives of the following function.

1. ## Find the first and second derivatives of the following function.

f (x) = 9x^4-8x^3+9x

f ' (x) =

f '' (x) =

2. $\
\begin{array}{l}
f(x) = 9x^4 - 8x^3 + 9x \\
f'(x) = 36x^3 - 24x^2 + 9 \\
f''(x) = 108x^2 - 48x \\
\end{array}
\$

3. would you show me how u arrived at these answers please

4. Originally Posted by plstevens
Memorise and apply the basic rule!!

If $y = ax^n\,$ then $\frac{dy}{dx} = n a x^{n-1}$.

5. plstevens, have you gotten up to the power rule as yet? i saw someone in another post do the derivative for you using the limit definition of the derivative and you followed it ok. how far along are you with derivatives?

6. Originally Posted by Jhevon
plstevens, have you gotten up to the power rule as yet? i saw someone in another post do the derivative for you using the limit definition of the derivative and you followed it ok. how far along are you with derivatives?
Since this is one of the many questions asked, I'd be very surprised if the power rule has not been taught ......

7. i'm doing ok i'm still tryna get the hang of it