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If (1, 2) is a limiting point of a coaxial system of circles containing the circle `x^(2)+y^(2)+x-5y+9=0`, then the equation of the radical axis, isA. `x+2y+9=0`B. `3x-y+4=0`C. `x+9y-4=0`D. `3x-y-1=0` |
Answer» Correct Answer - B The equation of a member of the family of coaxial circles having (1, 2) as the limiting point is `S_(1)=(x-1)^(2)+(y-2)^(2)=0 ` ...(i) Another member of the family of coaxial circles is given as `S_(2)=x^(2)+y^(2)+x-5y+9=0` ...(ii) The radical axis of (i) and (ii) is `S_(1)-S_(2)=0 rArr 3x-y+4=0`. |
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