#| BEGIN (Введите свое решение) |#
(define (good-enough? guess prev_guess)
  (< (abs (/ (- prev_guess guess)
             guess))
     0.0000000001))

(define (square x) (* x x))

(define (improve y x)
  (/ (+ (/ x (square y))
        (* 2 y))
     3))

(define (cubic-root-iter guess x)
  (if (good-enough? (improve guess x) guess)
      guess
      (cubic-root-iter (improve guess x)
                 x)))

(define (cube-root x)
  (cubic-root-iter 1.0 x))

; (cube-root 27)
; (cube-root 125)
; (cube-root 1000000)
#| END |#