At a distance \scriptstyle x along the line, the number of sections is \scriptstyle x/\delta x so that, .
\frac {V_\mathrm i}{V_x} = \lim_{\delta x \to 0} \frac {V_\mathrm i}{V_{xn}} = \lim_{\delta x \to 0} \left ( 1 + \frac {\delta Z}{Z_0} + \delta Z \delta Y \right)^{\frac{x}{\delta x}} .