#| BEGIN (Write your solution here) |#
(define (average a b)
  (/ (+ a b) 2))

(define (improve guess x)
  (average guess (/ x guess)))

(define (good-enough? guess x)
  (< (abs (- (improve guess x) guess)) 0.0001))
(define (sqrt-iter guess x)
  (if (good-enough? guess x)
      guess
      (sqrt-iter (improve guess x)
                 x)))

(define (square-root x)
  (sqrt-iter 1.0 x))
#| END |#