Using the following equation, find the center and radius of the circle. you must show all work and calculations to receive credit.

x2 − 4x + y2 + 8y = −4

Easy
group x and y's together

(x^2-4x)+(y^2+8y)=-4
complete the squaer for x's and y's
take 1/2 of -4 and square it
take 1/2 of 8 and square it
(x^2-4x+4-4)+(y^2+8y+16-16)=-4
factoer perfect square
(x-2)^2-4+(y+4)^2-16=-4
(x-2)^2+(y+4)^2-20=-4
add 20 to both sides
(x-2)^2+(y+4)^2=16
(x-2)^2+(y+4)^2=4^2

in form
(x-h)^2+(y-k)^2=r^2
center is (h,k)
radius is r
in our equation
center is (2,-4)
readius is 4