Question

What is the radius of a circle with the equation x2 + y2 – 14x + 10y = 250?

Answer 1

complete the square .

x^2-14x = (x-7)^2-(-7)^2 
             = (x-7)^2-49
y^2+10y = (x+5)^2-(5)^2
              =(x+5)^2-25
(x-7)^2+(y+5)^2-49-25=250
(x-7)^2+(y+5)^2=324
                         =sqrt 324
                         =18