could somebody help, me please?
1)find the center and length of a radius of each circle

a) x^2+y^2+8x-12x+43=0
I tried. and got stuck
(x^2+8x)+(y^2-12y)=-43
(x^2+8x=43)^2 + (y^2-12y+12)^2=-43+43+12
then....