If the quadratic equation a(b−c)x2+b(c−a)x+c(a−b)=0, where a,b,c are distinct real numbers and abc≠0. has equal roots, then a, b, c are in

As 1 is a root of the equation and equation has equal roots, the other root must be 1. Thus we have1= product of roots =c(a−b)a(b−c)⇒ a(b−c)=c(a−b)⇒ b=2aca+c⇒ a, b, c are in H.P.