add chapter 1 ex1

chapter_1/ex_1.rkt

@@ -0,0 +1,33 @@
+#lang sicp
+
+ 10 ;result 10
+
+(+ 5 4 3)  ;5+4+3=12
+
+(- 9 1) ;9-1=8
+
+(/ 6 2) ;6/2=3
+
+(+ (* 2 4) (- 4 6)) ;(2*4) + (4-6)=6
+
+(define a 3)
+(define b (+ a 1))
+
+(+ a b (* a b)) ;a is 3, b is a+1 which is 3+1 4 so that a+b+(a*b) that is 3+4+(3*4)=19
+
+(= a b) ;a is 3 and b is 4 the result is false
+
+(if (and (> b a) (< b (* a b)))
+    b
+    a) ;it is true that b>a --> (4>3) it is not true that (< b (* a b)) --> (4 > 12) so that b and a = 4
+
+(cond ((= a 4) 6)
+      ((= b 4) (+ 6 7 a))
+      (else 25)) ;a=4 = false, b=4 = true so that 6+7+3 = 16 
+
+(+ 2 (if (> b a) b a)) ; b>a is true so that 2+4 = 6
+
+(* (cond ((> a b) a)
+         ((< a b) b)
+         (else -1))
+   (+ a 1)) ;a>b is false, a<b is true, (+a 1) --> (3+1)=4 which is 4*4 = 16