Roots of Quadratic equation $x^2+x-2=0$  are

$x^2+2x-x-2=0$

$x\left(x-2\right)-1\left(x+2\right)=0$

$\left(x-1\right)\left(x+2\right)=0$

$\begin{array}{cc}x=1=0& x+2=0\end{array}$

$\begin{array}{cc}x=1& x=-2\end{array}$

Roots

$\left\{-2,1\right\}$