Question

The equation of a circle is x^2+y^2-4x+2y-11=0. What are the center and the radius of the circle? Show your work.

Answer 1

complete the square on the terms in x and y:-

(x - 2)^2 + (y + 1)^2 - 4 - 1 - 11 = 0
(x - 2)^2 + (y + 1)^2 = 16

So the centre is at (2,-1) and the radius = sqrt 16 = 4

Answer 2

I hope this helps you



x^2-4x+4+y^2+2y+1-16=0


(x-2)^2+(y+1)^2=16


x=2


y= -1