# Function notation minus one exponent?

Hi !

What does the notation mean exactly when a function has power minus one ?

For example i have seen the logistic function written as:

f(x) = f0[1 + exp(−βx)]^-1

gb7nash
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$$z^{-1} = \frac{1}{z}$$

For instance:

$$2^{-1} = \frac{1}{2}$$