The general form of the equation of a circle is x2+y2−4x−8y−5=0. what are the coordinates of the center of the circle?

(2,4)

x^2 + y^2 − 4x − 8y − 5 = 0      complete the square on x and y

( x^2 - 4x  + 4)  + ( y^2 - 8y + 16)  - 5 - 4 - 16  = 0   simplify

(x - 2)^2  +  ( y - 4)^2  -  25  = 0       add 25 to both sides

(x - 2)^2  +  ( y - 4)^2   =  25

The center  is  ( 2, 4)