1)

The radical centre of the circle 

x2+y24x6y+5=0, x2+y22x4y1=0  and

x2+y26x2y=0=0 lies on the line 


A) x+y-5=0

B) 2x-4y+7=0

C) 4x-6y+5=0

D) 18x-12y+1=0

Answer:

Option D

Explanation:

 S1=x2+y24x6y+5=0

S2=x2+y22x4y1=0

S3=x2+y26x2y=0

 S1S2=02x+2y6=0x+y3=0 .....(i)

 S2S3=04x2y1=0   ......(ii)

 Solving Eqs.(i) and (ii) , we get

 x=76,y=116

(76,116)  satisfies the equation 18x-12y+1=0