Question 618306
Find the radius and the center of the circle.
Equation of a circle:(x-h)^2+(y-k)^2=r^2, (h,k)=(x,y) coordinates of center, r=radius
x^2+y^2+6x-8y-155=0
complete the squares
x^2+6x+y^2-8y-155=0
(x^2+6x+9)+(y^2-8y+16)=155+9+16
(x+3)^2+(y-4)^2=180
center: (-3,4)
radius √180