Answer:
2√2
Step-by-step explanation:
compare this equation with the standard equation of a circle centered at (h, k) with radius r:
(x - h)^2 + (y - k)^2 = r^2
(x - 5)^2 + (y + 7)^2=8
Clearly, r^2 = (radius)^2 = 8, and so the radius, r, is √8, or 2√2
