(define (square x) (* x x)) (define (avg a b) (/ (+ a b) 2)) (define (improve-guess guess x) (avg guess (/ x guess))) (define (isgood-guess? guess x) ( < (abs (- (square guess) x)) .001)) (define (try guess x) (if (isgood-guess? guess x) guess (try (improve-guess guess x) x))) (define (square-root x) (try 1))