Answer:
8. center: (-7,5)
radius: 9
Step-by-step explanation:
8. to find the center, you need to get the equation in the form of (x-h)^2+(y-k)^2=r^2
you can do this by completing the square:
x^2+y^2+14x-10y-7=0
x^2+14x+49+y^2-10y+25=7+49+25
(x+7)^2+(y-5)^2=81
so, the center is (-7,5) and the radius is 9
