If the equations $x^2+bx−1=0$ and $x^2+x+b=0$ have a common root different from $−1$, then $|b|$ is equal to :

Question

$\begin{array}{1 1} (1) \sqrt 2 \\ (2)2 \\ (3) 3 \\ (4) \sqrt 3 \end{array} $