Let x and y be real variables satisfying x2+y2+8x−10y−40=0. Let a=max(x+2)2+(y−3)2 and b=min(x+2)2+(y−3)2.
Then,
a+b=18
a+b=2
a−b=42
a⋅b=73
x2+y2+8x−10y−40=0 The center of the circle is (−4,5). its radius is 9. distance of the center (−4,5) from the point (−2,3) is 4+4=22. Therefore, a=22+9 and b=−22+9 ∴ a+b=18 a−b=42 a⋅b=81−8=73