Find the centre and radius of the following circles : `x^2 + y^2 + 6x -4y -12 = 0`

Explanation

`x^2 + y^2 + 6x -4y -12 = 0`
`therefore` 2g = 6, 2f = -4, c = -12
`therefore` g = 3, f = -2
`therefore` Centre of (-g, -f) = (-3, 2)
and radius = `sqrt(g^2 + f^2 -c)`
= `sqrt(9 + 4 + 12)` = 5