abhay
Last Activity: 7 Years ago
let the common root be z.
So, z2+az+b=0 and z2+bz+a=0 as per the given equations.
Equate them , z2+az+b=z2+bz+a
(a-b)z=a-b
so, z=1
put z in any of the 2 equations,
12 + b.1+a=0 or 12 +a.1+b=0
1+a+b=0 or 1+a+b=0
so from both the cases (a+b)=-1