#| BEGIN (Введите свое решение) |#
(define (abs a)
  (if (< a 0) (- a) a))

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

(define (cube x) (* x x x))

(define (good-enough-cube? guess x)
  (< (abs (- (cube guess) x))
     (* 0.00000001 guess)))

(define (improve-cube guess x)
  (/ (+ (/ x (square guess)) (* 2 guess)) 3))

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

(define (cube-root x)
  (cube-root-iter 1.0 x))
#| END |#