If the circles x2+y2+2ax+cy+a=0 and x2+y2−3ax+dy−1=0 interesect in two distinct points P and Q then the line 5x + by - a = 0 passes through P and Q for
(2005)
no value of a
S1=x2+y2+2ax+cy+a=0
S2=x2+y2−3ax+dy−1=0
Equation of radical axis of S1 and S2
S1−S2=0⇒5ax+(c−d)y+a+1=0
Given that 5x+by−a=0 passes through P and Q
⇒a1=c−db=a+1−a⇒a+1=−a2
⇒a2+a+1=0 ⇒a∉R.
Not real value of a.