Tolong bantu ya sama caranya

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

pusat(1,-2) melalui (5.4)
(x-a) (x1-a) + (y-b) (y1-b) =r^2
(x-1)(5-1)+(y-2)(4-2)=16
4(x-1)+2(y-2)=16
4x-4+2y-4=16
4x+2y-8=16
4x+2y-8-16=0
4x+2y-24=0