Applicare la formula: $\left(a+b\right)^3$$=a^3+3a^2b+3ab^2+b^3$, dove $a=x$, $b=-\frac{1}{5}y^2$ e $a+b=x-\frac{1}{5}y^2$

Applicare la formula: $\frac{a}{b}c$$=\frac{ca}{b}$, dove $a=-1$, $b=5$, $c=3$, $a/b=-\frac{1}{5}$ e $ca/b=3\cdot \left(-\frac{1}{5}\right)x^2y^2$

Applicare la formula: $ab$$=ab$, dove $ab=3\cdot -1$, $a=3$ e $b=-1$