The function ddd is defined by d(v)=2−13e4v+1d(v) = 2 - \frac{1}{3}e^{4v+1}d(v)=2−31e4v+1 for v∈Rv \in \mathbb{R}v∈R, where ddd is the displacement of a mechanical actuator and vvv is the input voltage.
Find d−1(x)d^{-1}(x)d−1(x) and state its domain.