;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-beginner-reader.ss" "lang")((modname 7.8.1) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ())))
(require installed-teachpacks/picturing-programs)

; Worked exercise 7.8.1

; 5x : num(x) num(y) -> num
(check-expect (5x 0 53) 0)
(check-expect (5x 50 17) 250)
(define (5x x y)
  ; x a number
  ; y a number
  (* 5 x)
  )

; always-zero : num(x) num(y) -> num
(check-expect (always-zero 7 45) 0)
(check-expect (always-zero 118 -3) 0)
(define ( always-zero x y)
  ; x a number
  ; y a number
  0
  )

(build3-image 50 50 5x always-zero always-zero)