If a and b arc positive numbers and each of the equations x2+ax+2b=0 and x2+2bx+a=0 has real roots, then the smallest possible value of (a + b) is _________.

a2≥8b and 4b2≥4aNow b2≥a⇒    b4≥a2≥8b (a>0,b>0)∴    b3≥8⇒b≥2                          (1)Again a2≥8b and b≥2⇒    a2≥16 or     a≥4                    (2)From (1) and (2), (a+b)least =6.