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

Applicare la formula: $-\left(a+b\right)$$=-a-b$, dove $a=x$, $b=-1$, $-1.0=-1$ e $a+b=x-1$

Applicare la formula: $ab$$=ab$, dove $ab=- -1$, $a=-1$ e $b=-1$