I think its The equation of a circle with its center at the origin is x2 + y2 = r2. Replacing the x and y in this equation with –5 and 12, respectively, you get (–5)2 + (12)2 = 25 + 144 = 169 = r2. The square root of 169 is 13, so the radius is 13.
v is negative for every x, meaning the domain is all values in R, whatever goes under the squared sign will come out as positive and the left out -ve sign will make V negative for all x in R
