Question

Find the radius and the coordinate of the centre of the circle whose equation is
2x² + 2y² – 6x + 10y + 9 = 0 

Answer 1

(x – ³/₂)² + (y +⁵/₂)² = ¹⁶/₄
Center = (9,t) = (3/2 – 5/2) = (1.5, -2.5)
r = √ 16/4 = 2
Or
x² + y² – 3x + 5y + ⁹/₂ = 0
x² + y² + 29x + 2fy + c = 0
-2g = -3 -2f = 5
G = ³/₂ f = ^-5/₂
Radius r =√ (f² + g² - c) = ²⁵/₄ + ⁹/₄ – ⁹/₂
r = √ 16/4 = 2