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

x2+bx−1=0x2+x+b=0               ….. (1)Subtracting, we get (b - 1)x - 1 - b = 0⇒ x=b+1b−1This value of x satisfies equation (1)⇒ (b+1)2(b−1)2+b+1b−1+b=0⇒ b=3i,−3i,0