Question

x2 −2x + y2 − 6y = 26 what is the radius

Answer 1

$r > 0\\\\(x-a)^2+(y-b)^2=r^2\\\\x^2-2x+y^2-6y=26\\\\ (x-1)^2-1+(y-3)^2-9=26\\\\ (x-1)^2+(y-3)^2-10=26 \ |+10\\\\(x-1)^2+(y-3)^2=36\\\\ r^2=36 \ \Rightarrow \ r=6$