Applicare la formula: $ax+by$$=\left(\frac{a}{mcd\left(a,b\right)}x+\frac{b}{mcd\left(a,b\right)}y\right)mcd\left(a,b\right)$, dove $a=0.144$, $b=-\frac{16}{25}$, $ax+by=0.144x^8-0.64y^4$, $ax=0.144x^8$, $by=-0.64y^4$, $x=x^8$ e $y=y^4$