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

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

Applicare la formula: $\frac{a}{b}c$$=\frac{ca}{b}$, dove $a=1$, $b=4$, $c=9$, $a/b=\frac{1}{4}$ e $ca/b=9\cdot \left(\frac{1}{4}\right)x^2a$

Applicare la formula: $\frac{a}{b}c$$=\frac{ca}{b}$, dove $a=3$, $b=2$, $c=9$, $a/b=\frac{3}{2}$ e $ca/b=9\frac{3}{2}xa^2$