The given circles are S1≡x2+y2+3x+7y+2p−5=0....(1) S2≡x2+y2+2x+2y−p2=0 ∴ Equation of common chord PQ is S1−S2=0[ From (i) and(ii) ] ⇒L≡x+5y+p2+2p−5=0 ⇒ Equation of circle passing through P and Q is S1+λL=0 ⇒(x2+y2+3x+7y+2p−5)&+λ(x+5y+p2+2p−5)=0 Given that it passes through (1,1), therefore (7+2p)+λ(2p+p2+1)=0 ⇒λ=−