The equation of a circle which has a center at (-5, 2) can be written as Ax^2 + 2y^2 + Bx + Cy = 40. Find the radius of the circle
+36915 I believe A will ahve to equal the y^2 coefficient ....or you will wind up with an ellipse rather than a circle....
2x^2 + Bx + 2y^2 + C y = 40
divide thru by 2
x^2 + bx + y^2 + cy = 20
Center is given as (-5,2)
(x+ b/2)2 + (y + c/2)^2 = 20 +..... - b/2 = -5
- c/2 = 2
so you have
(x+5)^2 + ( y - 2)^2 = 20 + 25 + 4
= 49 49 is r^2 so r = 7
x^2 + 25x + 25 + y^2 - 4y + 4 = 49
x^2 + 25x + y^2 -4y = 49 - 25 -4 = 20
2x2 + 2y2 + 50x + (- 8) y = 40 Check!
