Spiegare gentilmente i ragionamenti e i passaggi, argomentare.
$ \displaystyle\lim_{l \to +\infty} \frac{μ_0in}{2} \left[\frac{l+2x}{\sqrt{(l+2x)^2+R^2}} + \frac{l-2x}{\sqrt{(l-2x)^2+R^2}} \right] = $
$ = \frac{μ_0in}{2} \displaystyle\lim_{l \to +\infty} \left[\frac{l+2x}{\sqrt{(l^2+4lx+4x^2)+R^2}} + \frac{l-2x}{\sqrt{(l^2-4lx+4x^2)+R^2}} \right] = $
dividiamo i numeratori e i denominatori per l (elle)
$ = \frac{μ_0in}{2} \displaystyle\lim_{l \to +\infty} \left[\frac{1+2\frac{x}{l}}{\sqrt{(1+4\frac{x}{l}+4\frac{x^2}{l^2})+\frac{R^2}{l^2}}} + \frac{1-2\frac{x}{l}}{\sqrt{(1-4\frac{x}{l}+4\frac{x^2}{l^2})+\frac{R^2}{l^2}}} \right] = $
$ = \frac{μ_0in}{2} [1+1] $
$ B= μ_0in$