Answers to Quiz 6
3 points
15 minutes

Trace the evolution of 
1: (+ (- 5 (* 2 3)) (/ 10 2))





   (+ (- 5 6) 5)
   (+ -1 5)
   4






2: (define (p x y) (if (= x 0) y (p (- x 1) (+ (* x x) y))))
   (p 4 0)





  (p 4 0)
  (if (= 4 0) 0 (p (- 4 1) (+ (* 4 4) 0)))
  (p (- 4 1) (+ (* 4 4) 0))
  (p 3 (+ 16 0))
  (p 3 16)
  ...now we skip the if step ....
  (p 2 (+ (* 3 3) 16))
  (p 2 (+ 9 16))
  (p 2 25)
  ... now we skip the if step and the arithmetic evaluation steps
  (p 1 29)
  (p 0 30)
  (if (= 0 0) 30 (p (- 0 1) (+ (* 0 0) 30))))  .... you could skip this too
  30

So the shortest correct answer would be:
  (p 4 0)
  (if (= 4 0) 0 (p (- 4 1) (+ (* 4 4) 0)))
  (p 3 16)
  (p 2 25)
  (p 1 29)
  (p 0 30)
  30
because I asked you to include 1 example of tracing through the "if"

answers