Answer:
Given,
x2 + y2 – 4x – 6y – 12 = 0
Centre ( – g1, – f1) = (2, 3)
x2 + y2 + 2x + 4y – 5 = 0
Centre ( – g2, – f2) = ( – 1, – 2)
x2 + y2 – 10x – 16y + 7 = 0
Centre ( – g3, – f3) = (5, 8)
x1, y1 are the coordinates of the centre and so on.
=> 2( – 2 – 8) – 3( – 1 – 5) + 1( – 8 + 10)
=> – 20 + 18 + 2 = 0
The centres are collinear.