Applicare la formula: $\left(a+b+c\right)^2$$=a^2+b^2+c^2+2ab+2ac+2bc$, dove $a=\frac{2}{5}xy$, $b=-\frac{3}{4}x^2n$ e $c=1$

Applicare la formula: $x\cdot x^n$$=x^{\left(n+1\right)}$, dove $x^nx=\frac{4}{5}\cdot -\frac{3}{4}xyx^2n$, $x^n=x^2$ e $n=2$

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

Applicare la formula: $\frac{a}{b}\frac{c}{f}$$=\frac{ac}{bf}$, dove $a=4$, $b=5$, $c=-3$, $a/b=\frac{4}{5}$, $f=4$, $c/f=-\frac{3}{4}$ e $a/bc/f=\frac{4}{5}\cdot -\frac{3}{4}x^{3}yn$