Applicare la formula: $a+\frac{b}{c}$$=\frac{b+ac}{c}$, dove $a=x$, $b=-y$, $c=2$, $a+b/c=x+\frac{-y}{2}$ e $b/c=\frac{-y}{2}$

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

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