$ \displaystyle\lim_{x \to 0} \frac{ log_2(1+2x+x^2)}{4x} = $
$ = \displaystyle\lim_{x \to 0} \frac{ log_2 (1+x)^2}{4x} = $
$ = \displaystyle\lim_{x \to 0} \frac{ 2log_2 (1+x)}{4x} = $
$ = \displaystyle\lim_{x \to 0} \frac{ log_2 (1+x)}{2x} = $
Cambio di base
$ = \displaystyle\lim_{x \to 0} \frac{ ln (1+x)}{2ln(2)x} = $
$ = \displaystyle\lim_{x \to 0} \frac{1}{2ln(2)}\frac{ ln (1+x)}{x} = \frac{1}{2ln(2)}$