Equation of family of concentric circles to the circle x2+y2 + 6x + 8y- 5 = 0 is x2+y2 + 6x+ 8y + λ = 0 which is similar to x2+y2 + 2gx + 2fy + c = 0 Thus, the point (-3,2) lies on the cirlce x2+y2 + 6x + 8y + c = 0 ∴ (−3)2+(2)2 + 6(-3) + 8 (2) + c = 0 ⇒ 9 + 4 - 18 + 16 + c = 0 ⇒ c = -11