If the circles x^2 + y^2 + 2ax + c = 0 and x^2 + y^2 + 2by + c = 0 touch each other then

JEE Advanced Mathematics question

If the circles and touch each other then

Answer: (A)

Two circles touch iff their common chord (radical axis) meets them in coincident points.

Subtracting the equations: . Substituting in the first circle:

++2ax+c=0 ⇒ (1++2ax+c=0.

Equal roots: $=4c(1+{b

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Question ID VK-108926