Find Center and Radius of Circle?

Question

Find Center and Radius of x^2 + y^2 - 4x + 8y - 5 = 0.

Answer 1

(x ² - 4 x + 4) + (y ² + 8 y + 16) = 5 + 4 + 16
(x - 2) ² + (y + 4) ² = 25
Centre (2 , - 4)
radius 5

Answer 2

x^2 + y^2 - 4x + 8y - 5 = 0.
x^2 - 4x +y^2+ 8y - 5 = 0.
x^2-4x+4-4 +y^2+8y+16-16-5=0
(x-2)^2+(y+4)^2-4-16-5=0
(x-2)^2+(y+4)^2=25
(x-2)^2+(y+4)^2=5^2
so it is now in standard form
(x-a)^2+(y-b)^2=r^2
so center is(2,-4) and radius=5