The equation of the circle concentric with x2 + y2 – 3x + 4y – c = 0 and passing through (- 1, - 2) is
Given that we need to find the equation of the circle which is concentric with x2 + y2 - 3x + 4y - c = 0 and passing through (- 1, - 2).
We know that concentric circles will have same centre.
Let us assume the concentric circle be x2 + y2 - 3x + 4y + d = 0. ..... - (ii)
Substituting (- 1, - 2) in (ii) we get
⇒ (- 1)2 + (- 2)2 - 3(- 1) + 4(- 2) + d = 0
⇒ 1 + 4 + 3 - 8 + d = 0
⇒ d = 0
Substituting value of d in (ii) we get
⇒ x2 + y2 - 3x + 4y = 0
∴ The correct option is (b).