I just want to make sure I am doing this correctly

d/dx(e^5x + 1) = 5e^5x

and

find d2/dx2 (lnx)^3 = 6(lnx)

Printable View

- Jul 1st 2008, 09:28 PM10164064can someone please just double check
I just want to make sure I am doing this correctly

d/dx(e^5x + 1) = 5e^5x

and

find d2/dx2 (lnx)^3 = 6(lnx) - Jul 1st 2008, 09:43 PMMathstud28
- Jul 1st 2008, 09:47 PMChris L T521
The first one is correct.

However, the second one is missing something...

$\displaystyle \frac{d^2}{dx^2}(\ln(x))^3$

You need to apply the chain rule here...

$\displaystyle \frac{d}{dx}(\ln(x))^3=3(\ln(x))^2\cdot\frac{1}{x} =\frac{3(\ln(x))^2}{x}$

$\displaystyle \frac{d}{dx}\frac{3(\ln(x))^2}{x}=\frac{6\ln(x)-3(\ln(x))^2}{x^2}$

Hope this makes sense! :D

--Chris - Jul 1st 2008, 09:51 PM10164064
its to the second derivative right?

so is it

{6/x(lnx)}-{3(lnx)^2/x^2} - Jul 1st 2008, 09:54 PM10164064
Ok thanx for the clarification Chris.