if x and y are integers such that ( x + 1 ) ^ 2 is less than or equal to 64 and ( y - 1 ) ^ 2 is less than 64 , what is the sum of the maximum possible value of xy and the minimum possible value of xy ?
"( x + 1 ) ^ 2 < = 64 x < = 7 x > = - 9 ( y - 1 ) ^ 2 < 64 y < 9 y > - 7 max possible value of xy is - 9 × - 6 = 54 minimum possible value of xy is - 9 × 8 = - 72 - 72 + 54 = - 18 answer : b"
add(sqrt(64), sqrt(64))