# CS代考程序代写 (define (sqrt x)

(define (sqrt x)
(define (square y)(* y y))

;(define (good-enough? guess)
; (< (abs (- (square guess) x)) 0.001)) (define (good-enough? guess) (let ((tolerance 0.001) (difference (abs (- (square guess) x)))) (< difference tolerance))) (define (average x y) (/ (+ x y) 2)) (define (improve guess) (average guess (/ x guess))) (define (sqrt-iteration guess) (if (good-enough? guess) guess (sqrt-iteration (improve guess)))) (sqrt-iteration 1.0)) (let ((a 1) (b (+ 1 1))) (+ a b)) (define (letExample c) (let ((a 10) (b 7)) (+ a b c))) (letExample 13) (define (letEx2 x) (+ (let ((x 3)) (+ x (* x 10))) x)) (letEx2 5) #| (define (letEx3) (let ((x 3) (y (+ x 1))) ;error, x is undefined (* x y))) |# (define (letEx3) (let ((x 3)) (let ((y (+ x 1))) (* x y)))) (letEx3) (define (letEx3b) (let* ((x 3) (y (+ x 1))) (* x y))) (letEx3b) #|(define (usingDef x) (if (> x 0)
(begin (define y 7)
(+ x y))))|#
;(usingDef 17)

(define (usingLet x)
(if (> x 0)
(let ((y 7))
(+ x y))))
(usingLet 17)