Question

If the circles x2+y2+2cx+b=0 and x2+y2+cx+b=0 touch each other, then

Answer 1

Answer:

Since the circles touch each other, equation of the common tangent is S1– S2= 0

⇒ x = 0.

Putting x = 0 in the equations of the circles, we get y2+ b = 0.

This equation should have equal roots ⇒ b = 0.

Hence (C) is the correct answer.