# Thread: How would I attack this problem?

1. ## How would I attack this problem?

$f(x)= {\log}_{5}(5x^{2}+1)$

It's the base that's throwing me off.

I'm looking for the derivative

2. Originally Posted by Zanderist
$f(x)= {\log}_{5}(5x^{2}+1)$

It's the base that's throwing me off.

I'm looking for the derivative
Use the change of base formula: $\log_a b = \frac {\log_c b}{\log_c a}$

$f(x) = \frac 1{\ln 5} \cdot \ln (5x^2 + 1)$