Question

Find the center and radius of the circle whose equation is x^2+2x+y^2+4y-11=0

Answer 1

you want to end up in this form:
(x-h)^2 + (y-k)^2 = r^2

have you used completing the square?
that is how you do this problem

Answer 2

I got the center as (2,1) and the radius as (-6,2)

Answer 3

hmm well radius is a length not a point
and the center is incorrect

Answer 4

I got this vertex now 2, -6

Answer 5

how are you getting this? if you dont show steps i cant know what you are doing wrong

also vertex if for parabolas ..... circles dont have vertex, only center and radius

Answer 6

completing the square

(x^2 +2x + ?) = (x+a)^2

--> (x+a)^2 = x^2 + 2ax + a^2

--> x^2 +2x +? = x^2 +2ax +a^2

therefore a = 1 and a^2 = 1

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

Answer 7

do same thing for y

(y^2 +4y) = (y+2)^2 -4

now you have

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

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

center: (-1,-2)
radius = sqrt16 = 4