Ricordiamo il limite notevole a cui fare riferimento
$ \displaystyle\lim_{x \to 0} \frac{(1+x)^k -1}{x} = k $
nel nostro caso
$ = \displaystyle\lim_{x \to 0} \frac{(1+x^3)^{\frac{1}{4}} -1}{x^3(1-x)} =$
$ = \displaystyle\lim_{x \to 0} \frac{(1+x^3)^{\frac{1}{4}} -1}{x^3} \cdot \frac{1}{1-x} = \frac{1}{4} \cdot 1 = \frac{1}{4}$
limiti notevoli.
lim x--->0 [(1 + f(x) )^k - 1] / f(x) = k;
radice quarta (1 + x^3) = (1 + x^3)^(1/4);
{[(1 + x^3)^(1/4) - 1] /x^3} * 1/(1 - x)
lim x ---> 0 [(1 + x^3)^(1/4) - 1 /( x^3) = 1/4;
lim x ----> 0 [1/(1 - x)] = 1;
limite = 1/4 * 1 = 1/4.
Ciao @ris