Question

What is the center and radius of the circle with equation x2 + y2 + 6x + 16y + 64 = 0?

Answer 1

Hello,
 
By making factors:
$x^2+y^+2+6x+16y+64=0\\ x^2+6x+9+y^2+16y+64-9=0\\ (x+3)^2+(y+8)^2=9\\ radius=3$