8. (x + 6)^2 + (y - 7)^2 = 81
9. The radius = sqrt [ (-6 - 0)^2 + ( -8 - 0)^2 ] = sqrt (100) = 10
So...the equation is (x + 6)^2 + (y + 8)^2 = 100
10. We have
( 3 - h)^2 + ( -1 - 7)^2 = 100 simplify
3^2 - 6h + h^2 + 64 = 100
h^2 - 6h + 73 = 100
h^2 - 6h - 27 = 0 factor
(h - 9) ( h + 3) = 0
Setting each factor to 0 and solving for h we have that h = 9 or h = -3