Determine whether the equation represent a circle or not : `x^2 + y^2 + 6x - 8y + 50 = 0`

Determine whether the equation represent a circle or not : 5x^2 + 5y^2 + 4x - 8y - 16=0

Determine whether the equation represent a circle or not : 3x^2 - 3y^2 + 4x-6y+ 10=0

Determine whether the equation represent a circle or not : 5x^2 + 5y^2 + 2xy + 4x-y+2=0

Determine whether the equation represent a circle, a point or no circle : x^2 + y^2 - 6x - 8y+25=0

Determine whether the equation represent a circle, a point or no circle : x^2 + y^2 +x-y=0

Determine whether the equation represent a circle, a point or no circle : x^2 + y^2 + 2x + 10y + 26=0

Examine whether the following equation represents a circle or not : 4x^2 + 4y^2 + 12x + 8y+40=0

Determine whether the equation represent a circle, a point or no circle : 2x^2 + 2y^2 -24x + 8y+120 = 0

Examine whether the following equation represents a circle or not : 3x^2 + 3y^2 + 2xy + 3x + y = 0

Determine whether the following represents a circle , a point or no circle : (i) 1- x^(2) - y^(2) = 0 (ii) x^(2) + y^(2) + 2x + 1 = 0 (iii) x^(2) + y^(2) - 3x + 3y + 10 = 0 .