Which of the following equations represents a cirlce? If so, determine its centre and radius
`x^2 + y^2 + 4x + 2y + 14 =0`.

Find the centre and radius of the circle : x^2 + y^2- 4x- 8y- 45 = 0 .

Find the centre and radius of the circle : 2x^2 + 2y^2- x=0 .

Find the equations of the following curves in cartesian form. Wherever the curve is a circle, find its centre and radius : x= at^2, y=2at .

Find the centre and radius of the circle : x^2 + y^2+ 8x + 10y- 8 =0 .

Find the centre and radius of the circle : x^2 + y^2- 8x+ 10y- 12 = 0 .

Find the centre and radius of circle 5x^(2)+5y^(2)+4x-8y=16.

In the following, find the centre and radius of the circles.:- x^2 + y^2 -4x -8y -45 = 0

Determine whether the following represents a circle, a point or no circle : x^2 + y^2+ 2x+ 10y+ 26=0 .

If the equation lambda x^2+(2 lambda-3)y^2-4x-1=0 represents a circle, then its radius is :