Question

Regina is trying to sketch a circle on graph paper with the equation x2+y2−2x+22y+1=0
. Calculate where she would need to graph the center and radius of the circle by completing the square.(1 point)

center= (−2,22)
, radius=41

center= (−22,2)
, radius=41

center= (−1,11)
, radius=11

center= (1,−11)
, radius=11

Answer 1

Complete the square:

x^2 − 2x = (x − 1)^2 − 1
y^2 + 22y = (y + 11)^2 − 121

Substitute: (x − 1)^2 − 1 + (y + 11)^2 − 121 + 1 = 0 → (x − 1)^2 + (y + 11)^2 = 121.

So center = (1, −11), radius = 11.