Question

What is the base of f(x)?

Answer 1

This curve can be described by
$f(x)=-\log_{2}(x)=\dfrac{\log(x)}{-\log(2)}=\dfrac{\log(x)}{\log(2^{-1})}\\=\log_{\frac{1}{2}}(x)$

The base of the logarithm can be considered to be either 2 or 1/2.