# Math Help - Another second derivatives question. :(

1. ## Another second derivatives question. :(

Struggling with another question.

$f(x)= sinh^-1 (5x)$

Then i went to this

$f'(x)= 5 (1/(1-5(x))^2)$

Not sure what to do after that.

2. ok
$f(x)=sinh^{-1}(5x)$
$f'(x)= \frac{(5x)'}{1+(5x)^2}=\frac{5}{1+25x^2}=5(1+25x^2 )^{-1}$
$f''(x)= this..... for..... you....
$

3. $f''(x)= -5 (50x) (1+25x^2)^-2$

Is that correct for the second derivatives?

Cheers

4. Yeah it is correct