A value of b for which the equations x2+bx-1=0 and x2+x+b=0 have one root in common, is

Let α be a common root of the given equations.Then,  α2+bα−1=0                            …(i)α2+α+b=0                               …(ii)On subtracting, we get(b−1)a=b+1>a=b+1b−1Substituting the value of α in (i), we get(b+1)2+b(b+1)(b−1)−(b−1)2=0⇒   bb2−1+4h=0⇒  bb2+3=0⇒b=0,±i3