問1.9
(define (+ a b)
(if (= a 0)
b
(inc (+ (dec a) b))))(+ 4 5)
(inc (+ 3 5))
(inc (inc (+ 2 5)))
(inc (inc (inc (+ 1 5))))
(inc (inc (inc (inc (+ 0 5)))))
(inc (inc (inc (inc (5)))))
(inc (inc (inc (6))))
(inc (inc (7)))
(inc (8))
9(define (+ a b)
(if (= a 0)
b
(+ (dec a) (inc b))))(+ 4 5)
(+ 3 6)
(+ 2 7)
(+ 1 8)
(+ 0 9)
9