Applicare la formula: $\frac{b^na^n}{c}$$=\frac{expand\left(ab\right)^n}{c}$, dove $a^n=\left(x-1\right)^2$, $a=x$, $b=x-1$, $b^n=x^2$, $c=\left(x+1\right)^2$, $b^na^n=x^2\left(x-1\right)^2$, $b^na^n/c=\frac{x^2\left(x-1\right)^2}{\left(x+1\right)^2}$ e $n=2$