Applicare la formula: $\frac{b^na^n}{c}$$=\frac{expand\left(ab\right)^n}{c}$, dove $a^n=\left(x-5\right)^3$, $a=x$, $b=x-5$, $b^n=x^3$, $c=\left(x^2+5\right)^7$, $b^na^n=x^3\left(x-5\right)^3$, $b^na^n/c=\frac{x^3\left(x-5\right)^3}{\left(x^2+5\right)^7}$ e $n=3$