Applicare la formula: $\left(a+b\right)^3$$=a^3+3a^2b+3ab^2+b^3$, dove $a=\frac{2}{5}ax$, $b=-\frac{10}{3}a$ e $a+b=\frac{2}{5}ax-\frac{10}{3}a$

Applicare la formula: $\left(ab\right)^n$$=a^nb^n$

Applicare la formula: $\frac{a}{b}c$$=\frac{ca}{b}$, dove $a=4$, $b=25$, $c=-10$, $a/b=\frac{4}{25}$ e $ca/b=-10\cdot \left(\frac{4}{25}\right)a^2x^2a$

Applicare la formula: $x\cdot x^n$$=x^{\left(n+1\right)}$, dove $x^nx=-\frac{8}{5}a^2x^2a$, $x=a$, $x^n=a^2$ e $n=2$