Question

Find the center and radius of the circle with equation x2 + y2 - 6x + 10y + 9 = 0.

center ( ? , ? )
radius ?

Answer 1

just complete the squares for x and y:

x^2-6x + y^2+10y = -9
x^2-6x+9 + y^2+10y+25 = -9+9+25
(x-3)^2 + (y+5)^2 = 25

I assume you can take it from there, eh?