If f(x)=5xf(x) = 5^xf(x)=5x, what is f−1(x)f^{-1}(x)f−1(x)?
f^{-1}(x) = \frac{1}{5^x}
f^{-1}(x) = \log_{5}(x)
f^{-1}(x) = \ln(x) / \ln(5)
Both b and c