Find the center and radius of the circle whose equation is x^2 − 7x + y^2 + 9y −1 =0
Complete the square for x and y
(x-3.5)^2 + (y+ 4.5)^2 = 1 + 12.25 + 20.25 <=========== red part is r2
center = (3.5 , -4.5)
+37167 
