Question

Find the center (h,k) and radius of the following circle.

x^2 + y^2 - 6x - 2y + 1 = 0

My answer is center= (-3,-1) and radius of 1. Am I correct?

Answer 1

x^2-6x +9 + y^2-2x+1=9 I added 9 to both sides.

(x-3)^2+(y-1)^2=3^2

I get center (3,1) and radius of 3

Answer 2

why 9?