Applicare la formula: $\left(a+b\right)^2$$=a^2+2ab+b^2$, dove $a=\frac{x}{8}$, $b=\frac{-y}{7}$ e $a+b=\frac{x}{8}+\frac{-y}{7}$

Applicare la formula: $\left(\frac{a}{b}\right)^n$$=\frac{a^n}{b^n}$, dove $a=x$, $b=8$ e $n=2$

Applicare la formula: $\left(\frac{a}{b}\right)^n$$=\frac{a^n}{b^n}$, dove $a=-y$, $b=7$ e $n=2$

Applicare la formula: $\frac{a}{b}\frac{c}{f}$$=\frac{ac}{bf}$, dove $a=1$, $b=4$, $c=-y$, $a/b=\frac{1}{4}$, $f=7$, $c/f=\frac{-y}{7}$ e $a/bc/f=\frac{1}{4}x\frac{-y}{7}$